While spacecraft have sent back images of the far side of the Moon, until that was possible we could only see one side of it. Wayne Schlingman explains why that was.
Now the Moon takes one trip around the Earth in the same amount of time it takes to make one rotation around its own axis: about 28 days. From Earth, we always see the same face of the Moon; from the Moon, the Earth stands still in the sky.
All sides of the moon experience night and day just like we do here on Earth. All sides have equal amounts of day and night over the course of a single month. A lunar day lasts about two Earth weeks.
Here is a short video.
I wonder if the flat Earthers think that the Moon is flat too. You would think that the fact that we see only one side of the Moon would make a stronger case for the flatness of the Moon than the case they have for the flatness of the Earth.