At this stage, your child has matured a lot intellectually. He is friendly with his peers and is fond of them. He is now familiar with known people and socializes more as well. He is more independent in his approach. He converses with everyone and knows what to talk. He also leaves the conversation when required to do so.
What you can do
Now that your child has developed a knack of conversation, talk with him as much as you can. Speak politely and to the point. Children always follow their parent. Their behavior is always a reflection of what happens at home.
Your child is very small and people try to be friendly and talk to him. Sometimes they even misuse this opportunity and try to gain information about various things. So ask him not to talk to strangers. Make sure that he knows how important it is not to disclose his family, school and residential address to a stranger.
You can even teach him the kind and polite behavioural traits of greeting and thanking people.