We use the present simple to talk about actions we see as long term or permanent. It is a very common and very important tense.
Here, we are talking about regular actions or events.
* They drive to the office every day.
* She doesn't come here very often.
* The news usually starts at 6.00 every evening.
* Do you usually have bacon and eggs for breakfast?
Here, we are talking about facts.
* We have two children.
* Water freezes at 0° C or 32° F.
* What does this expression mean?
* The Thames flows through London.
Here, we are talking about future facts, usually found in a timetable or a chart.
* Christmas Day falls on a Monday this year.
* The plane leaves at 5.00 tomorrow morning.
* Ramadan doesn't start for another 3 weeks.
* Does the class begin at 10 or 11 this week?
Here, we are talking about our thoughts and feelings at the time of speaking. Although these feelings can be short-term, we use the present simple and not the present continuous.
* They don't ever agree with us.
* I think you are right.
* She doesn't want you to do it.
* Do you understand what I am trying to say.