The vocabulary your kiddo now is pretty extensive. 4-5 years is the age when your child’s language skills take a great leap forward. He might be adept at using different words and even rhyming them with others.
What you need to know
This is the age where he begins to pronounce words better. He would be able to understand the sounds of words clearly. This is primarily a reason why he starts understanding rhyming and similar sounding words.
His improved vocabulary and understanding of the word sounds also improve his conversational skills better. He would start becoming a better listener. He would be able to listen to people talk and would analyse and learn from the way different words are pronounced. Use this time to help him improve his grammar too.
What you need to do
Talk to your kid. Use new words when you talk. This can help him build his vocabulary further. He would be beginning to use words well to frame more complex sentences. ead to him more. This can expose him to more words and help him understand word usage better. Teach him the concept of rhyming words if he has not himself started talking about it. He would be instantly interested and might often surprise you with his own discovery of rhyming sets of words.