N.D.
Hello! I'm so happy for you! I'm a speech pathologist and I love hearing stories like this- it actually means he was still progressing with his receptive language- or what he could understand- even though his expressive language wasn't quite where it needed to be yet! Are there any words that you feel he missed that you would like him to say to help him communicate? If so, lot's of modeling of those words in various situations will help him along. You can add them to what he is already saying (which is a strategy called expanding.) For example, if the word "ball" is not in his expressive vocabulary yet- and it is a word you would like him to say- then when he is playing with it you could model "go ball"! Or if he says the word "roll" while playing with the ball you could expand with "roll ball".
Btw- what is his age? And is he getting frustrated with communication at all?
Good luck and have fun with your language developing kids!
feel free to email on this site if you want. :-)