How do children learn to talk?

Observation, hearing and mimicking.

Babies notice the sounds of the language they hear around them very early. They understand some language before they start to speak. They recognize words that their caregivers use over and over again with them. Eventually, they start to try to say those words they understand, usually one word at a time- "more" when they want more food, for example, or "cookie" when they want a cookie. When adults understand and respond, it reinforces their efforts. Then they start to add verbs- "want cookie", etc. We know that children do NOT just repeat what they hear- they deduce rules and try to apply them, so most children will say things like "I eated it all up" because they have realized that they need to add something to talk about a past event, and they overgeneralize the rule.

It's a natural way of learning language that is being applied to second language learning. First language learners do not learn through grammar explanation and explicit teaching, and grammar rules don't help second language learners much either.

Children under the age of seven have a unique cognitive ability to absorb multiple languages. They learn them by using their auditory and visual senses. It is not necessary to "teach" something at this age that they have an innate ability to learn. After this age, language acquisition becomes much more difficult, and must be actively taught. If a child has not learned a first language by this point, it is nearly impossible, and serious professional intervention is necessary in order for the child to learn to communicate.

This is why language immersion is the best way to learn even for adults. Hearing the language in the correct context from a native speaker, and being forced to use it out of necessity helps the learner become fluent.

As children get older, they start to learn things themselves. They learn to sense, touch and feel things. They also learn to talk, read, tie their shoes laces, get dressed etc.

First kids capture everything by observing .And they try to sound the words that we use in front of them.And then hearing is the process taking around them.Then they try to express as they can.