The Marvel Cinematic Universe is a franchise consisting of film and television adaptations of Marvel Comics publications produced by Marvel Studios. The franchise is notable for being the first superhero film franchise to have characters and plot points from different titles crossover.
Hawkeye is a superhero and Agent of SHIELD in the comics and MCU. However, his character in the MCU is quite different than that of his comics incarnation; his comics incarnation is deaf, and wears a somewhat outlandish purple suit. The MCU version of the character, portrayed by Jeremy Renner, does not do much independent superheroing and acts mostly as an agent of SHIELD or the Avengers, wearing a mostly black tactical suit.