The difference between DO and DOES is not difficult to understand.
DO is a verb and DOES is the third person singular of that verb in the present tense. Every other person in the conjugation uses DO.
When the subject is I, you, we, or they, we use DO.
I do my homework every day.
Do you know the answer?
I don’t see it.
We don’t want any cake.
They do it for fun.
We do it every day.
Why do you ask?
When the subject is he, she, or it, we use DOES.
He does his homework every day.
Does she know the answer?
She doesn’t see it.
He doesn’t want any cake.
He does it for fun.
She does it every day.
Why does she want to know?
