Viewpoint is just another word for point of view. The point of view of a story is pretty much the angle of what sort of things are considered in. The opinions and feelings of your characters, it can also tell what sort of narration a story is in.
Such as:
First person point of view uses the words 'I' and 'we'.
I felt as though I was stuck in an endless cycle, and there was no way out.
We went to the park and saw many geese.
Second person point of view uses words like "you" and "your"
You picked up the glass of water and drank it. It felt odd going down your throat.
Third person limited is when you limit your third person view to only a single character.
Jane felt as though this was all rather unfair.
Third person omniscient is when you tell your third person point of view using many different characters.
Both Maxwell and Leon felt as though this was going to be a long night, however Jenson felt as though tonight was going to be fun.
Two ways you can use it is applying it to real life, or other things. You can use it in first person, second person, third person limited, and third person omniscient.
Hope this helped :)!
