He is learning his vocabulary from your vocabulary. The words that you speak around him become his language. You can constantly add to his vocabulary and help him to express himself by talking to him all day long. Here are some specific suggestions:
Narrate your child’s play, describing what he does. Talk about colors, shapes, and sizes and when you see him struggle, remind him to ask for help. Try to give him the opportunity to ask for help before you intervene. Even if he just attempts to say “help” or sometimes even using eye contact is appropriate. Try not to jump in until he uses his voice or gestures to ask for help.
Talk about body parts and ask your toddler to point to their ears, nose, eyes, and belly so they are familiar with each body part. Then you can ask your toddler to point to your ear, nose, eyes, and belly so that he begins to differentiate himself from you and start to learn some possessive pronouns such as “yours” and “mine.”
Observing animals in the world (even in a book or a toy) and making animal sounds is a great way to teach your young toddler language and articulation (use of their mouth to make sounds). Encourage your toddler to make animal sounds.