At the age of 3-4 years, your kid is now able to speak and describe familiar things. Her speech is clear and influenced by the environment she is growing in. She understands all that is happening and can express it in detail. She can talk in long sentences and has a good vocabulary.
What you need to know:
Encourage your child to speak. Play games like picture talk where you will talk about a picture first and then ask her to talk on the same. She will get ideas to talk on familiar pictures and at the same time she will gain some new information from your speech. Take her out to play with friends in the park, playground, visit neighbourhood places like market, temples, post offices, hospitals, banks, etc. Talk on things you see there and its importance in everyday life. The more you describe the things she can see the more you will increase her knowledge. Use simple words to describe and whenever any new word is introduced try to use it and make her use it to. Correct her whenever required.