Infants begin life with no other language than their cries and grunts.  As their language mechanism matures, they make more and more sounds.  They also can communicate their wants and needs with gestures and cries.

At about one year, the first word appears.  Nouns come first, then verbs, then adjectives and adverbs, with pronoun appearing last.

The language ability depends in part on maturation, but also on other factors.  Those children who talk earliest will on the average.  Girls tend to talk a little earlier than boys. Single children tend to talk earlier than twin.  Twins with a more stimulating environment make more rapid progress in language development than those with a poorer environment.