Just because it is the most common question, doesn't mean it is the easiest one to answer.
Children often produce their first meaningful word at around one year of age.
Parents may attempt to teach young children words that are too abstract to have any meaning for the child. Concepts such as numbers, shapes or colours are not usually among the earlier words that a child says. Children like to talk about things that are very real to them. It is common for parents to focus on teaching children names of things, so the child can go around the room labeling every object in sight. These two-word phrases are the beginnings of the grammatical sentences that we use in adult language.