Adonis is a name coming from a popular youtuber who talks about self-improvement and no-fap, Adonis is an example for the a man who is the best of the best and uplifts others. In basic terms it's a way to call someone a chad without calling them a chad.
Billy: Yo bro, thanks for helping me out at the gym!
Ruben: No worries, thats what i'm here for.
Billy: Your a real Adonis!