They do not work on Sundays.    (We don't work on Sundays either.)

You will be glad you know about do and don't (and does and doesn't) now, because they will help you with questions.

Remember last lesson when we asked Will you work...? We put the subject (you) right between Will and work. Well, now we are going to do the same thing with Do.  Do you work? is a question just like Will you work?  They are both "helping" verbs like can, but of course will is for the future.

Do I work?
Do you work?
Does she work?
Do we work?
Do you work?
Do they work?

If someone asks  Do you work? you can answer No, I do not OR you can answer No, I don't.  It means exactly the same. (Sometimes people use the longer form to stress the word not.)

In just one case, 3rd person, we use the word Does.  Does she work? Yes, she does. No, she does not (or doesn't).

When you get to "Wh" questions it works about the same, but....