What exactly is the "present simple"?  It is the verb form we use to talk about things in general, things that repeat, or things that are generally true.  These would be things like eat, sleep, the sky is blue, the sun goes down every day, people have two eyes not three, etc.

We have to change the verb according to who is doing the action.  We will start with the verb "to work."

I work (I work every day.)

You work (You work at the library.)

He/she/it  works (She works at the local zoo.)

They work (They work very hard.)

We work (We work in the factory.)

Some examples of these are:

"I go to work every day at 7:45." - This means that almost 100% of the time I go to work at 7:45, not 8:00, not 6:00, but at 7:45.

"The sun sets in the west." - This is 100% true.  This is a fact and will not change.

"Christmas is every December." - This is a fact and it also repeats.  Christmas is always in December and so every December, no matter what happens, Christmas will occur.