Generally speaking, children are around 1 year old, which is the primary stage of language. At this time, you will find that apart from mom and dad and some single-word idioms, the baby can understand much more than he knows, so at this time, the baby may complete some simple instructions and use his fingers to know objects or people around him. Babies may often use one word to express multiple meanings, simple instructions are well done, and even some irrelevant ones can be pointed out. 12- 18 months old children can use about 20 words. 18-24 months old children can make sentences with words, usually hundreds of words. Children aged 24-36 months can communicate with each other in sentences, express their emotions, intentions, quantity, names, ages, genders, and names of commonly used objects, or complete two or three instructions in succession. After 3 years old, the baby will have space nouns, time nouns and pronouns. Children aged 4-5 can speak complex sentences. Generally speaking, 7-24 months old children are the key period for language understanding, and 2-3 years old children are the key period for oral expression. During this period, we should pay attention to oral expression. Children are 2-3 years old, which is a period of language explosion. At this time, the baby's language progress is particularly fast, and he can communicate with more complicated sentences, especially like asking questions. As long as he talks, he may not stop. Many children treat language at this time as if they had got their favorite toys. They will talk all the time and even ask questions. In fact, at this time, parents must correctly treat their children's performance, and understand that this is a manifestation of brain development, indicating that the baby's thinking ability and cognitive desire have improved. Be sure to answer your baby's questions patiently and don't be upset, otherwise it will dampen your baby's desire to speak. After the baby is over 3 years old, his pronunciation is basically accurate. He can correct some grammatical mistakes from the communication with adults and form a normal language without causing some obstacles in the communication process.