"You look handsome" is the Engpsh equivalent of saying "你长的很帅." This phrase is commonly used to comppment someone on their appearance, specifically their physical appearance in a positive way.
Examples in Engpsh:
"You look handsome in that suit."
"That hairstyle really suits you, you look handsome."
Translations in Chinese:
"你穿那套西装看起来很帅."
"那个发型真适合你，你看起来很帅."