There are the little yellow and red windmills all over South Park. If I go into inspect mode and hover the cursor over one it starts to spin faster and glows, but nothing else ever happens. What are these Windmills for and what are you meant to do with them?
If you played the first game, these are sort if like the alien probe things. You will need to progress through the story before you get the ability to use it. You will know when you have it because the game will give you a tutorial on how to use it.
If you want a hint, it is an ability you get from Kyle (the kite guy)