Tafsiri - Kifini-Kiingereza - Lapsia ei voi

This is kind of too short and could be translated different ways depanding on context. Anyway lapsi = child, lapset = children and lapsia form indicates most likely that someone can't do something with/to children.

Children can't be let out = Lapsia ei voi päästää ulos
Children can't be (exist) = Lapsia ei voi olla
Children can't be (something) = Lapset eivät voi olla (jotain)