It’s fairly simple. The more you expose your child to information and experiences, the more they will soak it up. We have recently started colors and even though we aren’t really able to recognize colors correctly, we are slowly getting there.
The key is not to sit with your child and ‘make’ them learn. Instead, play. Adapt your playtime into a fun learning experience and use the resources at hand to reinforce concepts.
We gather all objects of a particular color and simply play. ‘Oh look two orange cushions, put them on top of each other.’ ‘The orange lion is hungry, feed him the orange ring’
It may not be overnight. It is a slow process. But what’s the hurry. There was never a functioning adult who didn’t know colors.