What is the meaning of the proverb Tell me who your friends are and i will tell you who you are?

Absolutely. Unless you are very lonely and are friends with anyone who bothers to look your way, or weak enough to surround yourself with people you secretly hate, but cant find the strength to let go of.

People are similar to the friends they make -- you can look at the personalities and characters of someone's friends and tell what sort of person they are.

Answer:

Most definitely. Ever heard a similar expression, "people will judge you by the company you keep?" People generally will choose as their friends like minded individuals. Sometimes that is a good thing, but unfortunately some of these friends people choose can be toxic and not good for them. We all have to be willing to see toxic relationships for what they are and have the courage to let go. Choose friends who inspire you, who make you feel confident and good about yourself. See Young People Ask book on jw.org