translation says ''the children'' but it's written ''copii'' and not ''copiii'', why is this happening?
It is because of the preposition. I think the only preposition that can be followed by a noun with the article is cu
It's a little complicated... in the accusative case (direct object), îi is used for the masculine gender, and le is used for the feminine. In the dative case (indirect object, replacing bărbatului, fetei, fraților, etc.), îi is used for ALL singular nouns, and le is used for ALL plural nouns, regardless od gender. In terms of the contractions, they're normally used in compound tenses (like past: i-am dat, le-am dat; and conditional: i-ar da, le-ar da. Also in the subjunctive, you would say, vreau să-i dau. I hope that helps... Romanian grammar can be pretty tough. I think you just have to get a feel dor it mostly.