What does it mean when someone says "You look quite chill"?
***** NOT A TEACHER *****
(1) I don't think that I can help you with your particular question.
(2) But you may wish to know that some younger people in the United States use "chill" or "chill out" like this:
TOM: We have been waiting in line for one hour. I'm going crazy. I'm really, really angry.
MONA: Chill out! = Calm down! Don't get so excited!
Have a nice day!
"an adjective used to describe someone who you think is very cool, someone you'd like to spend time with. is generally used with a preceeding adverb, such as very, pretty, definitely, etc.
She is definitely chill; I'd like to be with her."
Look here for some other slang uses:
Urban Dictionary: chill
PS: Don't expect other people to understand these terms if you use them. But that dictionary can help you with some slang meanings.