One of the parts of speech I think are important is a verb because it’s the only part of speech that shows or indicates past, present, and future tense. It is the main part of every sentence , and shows what the subject does or what state the subject is in.
Example
Sarah is driving the car (Tells us what she is doing )
She is an engineer (describes Sarah’s state of being )
Sarah is sleeping now. ( shows when the action is taking place)