Do you sing together?
Read together?
Singing repetitive songs like The Wheels on the Bus or Five Little Ducks Went out to Play is a good idea - he will hear singing, vocab, and learn a few phrases.
Rhyming books emphasise sounds of words and he will start joining in if you keep at it. You need to read a lot before this happens
Boring though it may be for you, reading the same books over and over may be very pleasant for him, and will reinforce the vocabulary.
Make sure you talk to him when you are doing ordinary things - but repeating words. For instance ' I'm pour, pour, pouring the bathwater', or 'you're crunch, crunch crunching the cracker'. Speak in short but full sentences, repeating verbs as shown. Repeat nouns too - ' Here's your toast - let's put the toast on the high chair tray - toast is so nice - yes, munch munch, munch the toast'.
Introduce animal sounds into your games. Get him to moo, woof, miow, quack, heehaw, tweet tweet, ribbit, neigh. If you have a book with pictures of animals, make a game of mimicking what they all say.