The word "really" in true essence is pronounced REAAAAAAALLLLLYY (most effective when pronounced for 4-7 seconds), and is a phrase used to express a feeling of astonistment, being extremely suprised about a particular event or often just used as a filler untill the speaker can think of something better to say. Indivudials are advised to refrain from using the term in serious settings though.
Example 1- (appropriate setting of really)
Speaker 1: Bro i just got dome from the girl of my dreams
Speaker 2: REAAAAAAALLLLLYYY?!
Speaker 1: yeah bro i did
Speaker 2: oh true thats legit bro
Example 2- (Inappropriate setting)
Speaker 1: Bro i think i got Mandy pregnant
Speaker 2: REEEEEEEAALLLLLLY?!
Speaker 1: Dawg, im not joking that shit is uncalled for
Speaker 2: My bad bro, best of luck with that rather unfortunate situation, much apologizes
Speaker 1: I appreciate the concern