You have bought a VPN account at one of the major VPN providers. You have done so, because you e.g. have a second residence in another country. You may even have a dual citizenship.
Let us assume that you are abroad and want to work with web services offered in your home country for its citizens.
You are abroad, but electronically you may need to operate as if you were located in your home country. There are a lot of services which check the geolocation of your IP and only serve you if you call from “inside” the country, i.e. if the IP is located there.