No. If you wanted to say "a girl is beautiful", there are a few options depending on your emphasis. This sentence in particular is trickier than others, for some reason. The first option would be ילדה אחת יפה - which means "one girl is beautiful". If you wanted to make it a bit more ambiguous, you would probably say ילדות הן יפות - "girls are beautiful". If you are talking about the idea of a girl being beautiful, you would say something along the lines of ילדה זה דבר יפֶה - "a girl is a beautiful thing".