So I guess they call it "technical terms"but in technical terms scopes are basically independent blocks of code. The code within a scope is this blocked off from "interfering" with other code. Basically limiting any unwanted side-effects. Working with helpers like Bootstrap is great but sometimes you might just want a few bonuses without it affecting your entire project. Here's a great article on the topic. Very great read.
Saving the Day with Scoped CSS
Saving the Day with Scoped CSS