It means, A tree has green leaves, And you can say both of 緑の葉のついた木and 緑の葉の木 The first one line you can describe more precisely, and it's included a sort of season, I guess.

Hi! 「ついた」 comes from the verb 「つく；付く」which generally means "to be attached; to be connected with; to stick; to cling", and on a lesser extent "to bear (fruit)", "to take root", etc. So I believe on one side,「緑の葉の(ついた木)」means "a tree (attached to the ground), with green leaves", and on another side「緑の葉 (の or が）ついた木」 "a tree with (bearing) green leaves".