It hides your traffic from the network you are sitting on by routing it through a company's server. You are not anonymous — you have moved who has to be trusted.
The drawing that proves the sentence above. It is the same card that is in the book.
Think of it as
mailing your letter from a different city, in a sealed pouch.
For example
On the café internet nobody around you can see what you are doing. The company you paid for that can.
This is one card out of 275.
The hundred words you meet most are free — the whole set, animated, in one file that works with no internet.
Volume 1 has all 275 in fifteen chapters, with Staying Safe the largest chapter on purpose.