Scope is a big idea in programming, so let's start at a high level.
Scope refers to where in a program a variable can be accessed. The idea is that some variables are unable to be accessed everywhere within a program.
Think of it like a an apartment building. Everyone who lives in the apartment building is under the global scope of the building and its manager. So, if there are rats in the shared laundry room, everyone has access to the laundry machines, and the rats.
Let's practice this by making some global variables.