Before children USE a variety of words, they must first understand a variety of common words.
Before children start talking, they SHOW us what they know and understand.
They use body language, make faces, and use gestures when they hear words they understand that show us "Oh, they KNOW what I just said". Your child may not yet be using facial expressions and gestures, they might just use body langage- that's okay.
Let's just think about ROUTINES such as
Eat, Sleep, Diaper Change, Wash Hands, Bath, Play, Nap, Go,
Think about it your child understands the WORD for the routine
I cannot tell you how many parents when asked "Does your child understand WORDS?" Responds to me with
"Yes, they understand! When I turn the water on in the bath tub they come running" or "Oh yeah, they understand words, they go to the kitchen and get their own snack or drink."
This is NOT understanding WORDS!
Hearing the water running? That's understands the environment, not words.
Going to the kitchen because that is where food and their drink is? Again, that's understanding the environment.
Let's think of some examples that give us evidence that a child understands words from ROUTINES!
You say "Time to get a BATH" and your child runs away (before you move to the bathroom) as they hate to get in to express "no, no, no! I heard you, but I don't want to get in the bath!" OR they run right to the tub and take their clothes off to express "Yes! Let's get a bath!" (Before you even head for the bathroom).
You ask "Hungry?" And your child jumps up and down and walks to the pantry before you even start to move.
You say "Oh, you need a diaper!" And they fuss, knowing you are about to mess with them before you even go get the diaper or take them to the changing table.
You ask "Do you need to wash your hands?" And your child looks at their hands and wipes them off and shows you to express "I mean they aren't that dirty."
You say "it's time to GO." And your child walks to the door or goes to where their shoes are.