Revenge mission. Sometime after Natasha gave her life to get the Soul Stone and help thwart Thanos' dastardly plans in Avengers: Endgame,
Essentially, the scene takes place mid-credits and it sees Yelena at Natasha / Black Widow's grave to mourn her passing in an emotional nod to her sacrifice in Avengers: Endgame.
In particular, Yelena ended the movie on a mission to free the other brainwashed Widows. However, in the post-credit scene for "Black Widow," set after "Avengers: Endgame" Yelena was now working for a mysterious figure called Contessa Valentina Allegra de Fontaine (aka Val), played by Julia Louis-Dreyfus.
Black Widow, pre-credits, might end with Natasha alive, but post-credits the story skips right to a depressing stinger: Florence Pugh's Yelena Belova visiting her sister's grave.
Yelena blips. When she returns, her first thought is to find Natasha, who the audience knows is already dead. The horrifying reality is that those who blipped didn't actually feel anything. One moment Yelena was in a bathroom, and the next the bathroom walls were a different color as five years went by in a snap.
Belova tackled Barton, knocking him onto the ice to fight him herself. Belova asked Barton to tell her what really happened on the day that Natasha Romanoff died. Barton told her that Romanoff had sacrificed herself to save the world, but Belova did not believe him.
Hawkeye revealed that Yelena was actually just 30 to 35 years old in MCU Phase 4. This is because, unlike Black Widow's age when she died, calculating Yelena Belova's age in Hawkeye entails factoring in the five years of her life lost during the Snap.
No funeral, but a tribute to Natasha as a character, nonetheless.
Turns out it's Contessa Valentina Allegra de Fontaine (Julia Louis-Dreyfus), the mysterious woman whom we first met in the Disney+ series The Falcon and the Winter Soldier.
By the end of the film, Yelena is so devastated by Natasha's death, that she's willing to listen to Val—a stranger—when she tells her that Clint Barton is responsible for Black Widow's demise (which occurred in Avengers: Endgame).
Yelena Belova
Since then, Belova has been seen in other Marvel projects including Hawkeye, and will reprise her role in the new Thunderbolts movie. That being said, it is unlikely that Belova would join the Avengers.
It's only seconds later that this is reaffirmed as Natasha whispers a tearfully permitted "let me go" before kicking free of Clint's grasp; the loss of contact replaced by a feeling of unbalance.
In a world where emotion is used for exploitation and manipulation, Natasha's love for her sister makes her especially vulnerable. By looking for Yelena or sharing the truth about her past, Natasha would put herself in a bad tactical position.
However, the emotional scene has led fans to question why Natasha Romanoff/Black Widow didn't receive a farewell scene after losing her life in the quest to obtain the soul stone. In an new interview with Entertainment Tonight, co-director Joe Russo explained that it's all to do, quite rightly, with closure.
"Scarlett talked to me about it: Her character would have hated a public funeral," Shortland told Variety about Natasha's modest gravesite in Ohio. "So I felt like the fact that she's buried in a really private place, in the boondocks somewhere, is perfect."
During her fight with Clint Barton, Yelena Belova found out the truth. Clint showed her how much he cared about Natasha by using her special whistle. It's something that Natasha doesn't share with just anyone.
Yelena Belova in Marvel Comics
At age 15, Yelena Belova is recruited and raised in the Red Room as a promising young assassin and the replacement Black Widow.
We know Natasha's ultimate fate though -- she sacrifices her life to obtain the Soul Stone and undo Thanos' genocidal Snap in Avengers: Endgame. We see the fallout of her decision in this movie's post-credits scene.
Portrayed by. Contessa Valentina Allegra de Fontaine is a noblewoman and the Director of the CIA, who had become interested in recruiting powerful individuals. De Fontaine personally recruited John Walker, who lost his position as Captain America, and Yelena Belova, offering her a chance to avenge her sister.
In case anyone was hoping to see Natasha Romanoff come back to the MCU, Scarlett Johansson is here to tell us she's officially hanging up her Black Widow jumpsuit for good. As one of the six original Avengers, Johansson played a key role throughout Marvel's Infinity Saga.
An upcoming Marvel Cinematic Universe film will serve as a sequel to the 2021's "Black Widow," according to Marvel Studios executive Andy Park.
In 'Endgame', Natasha sacrifices herself in order for Hawkeye to retrieve the Soul Stone on Vormir. She said, “It didn't surprise me that that was a choice that Nat would have made. I knew that she had to feel at peace with that decision and that she was doing it out of love.
Yelena Belova (Asexual)
Crimson Widow (Yelena Belova; Russian: Еле́на Бело́ва) is a fictional character appearing in American comic books published by Marvel Comics. She is depicted as a spy and was the second modern-era character to use the Black Widow name, but later took on the Crimson Widow name.
In universe, I think they explain it because Natasha has been in the West so long she now has an American accent. Yelena is still living in the East and so still has an accent (oddly, for a master spy/assassin). Out of universe: Scarlett Johansson can't do accents.