Could this be translated as 'look after your friends'?
I'd say "Watch out for your friends" or even "Watch over your friends" is more idiomatic in English.
The funny thing about "watch out for your friends" is that it could mean either that you should protect them from threats (watch out for = look after, protect), or that they may pose a threat to you (watch out for = beware, exercise caution around).
Is "guard your friends" OK?
Duolingo really needs a slower pronounciation...
"Watch your friends" should be correct
what about... Keep your friends
Wouldn't that be שִׁמְרוּ אֶת הַחֲבֵרִים?
לטפל בחברים שלך. Does it have the same meaning?
Well, טַפְּלוּ בּ־ seems fine to me.