Pozdrav, Doslovno prevedeno bi bilo: That who/which is worthy (valuable), one speaks about it/him. Je li ovo neka izreka kod Vas? Lp, Yifan

I have not heard this expression in English, but I would translate it this way: "He who knows him, should talk of him." I believe it implies that if we don't know the man, we should not say things about him. This phrase is written like a proverb in more of a poetic style than we would speak in common everyday English.

This looks like Serbian (I'm just guessing). Maybe you wrote English also, but the English didn't print?