The main two things that VPN does are:
Spoofing an IP address with a fake one - VPN changes your IP address to a machine address from another country. Your real address is hidden behind a new IP, you can visit sites without fear of restricting access from various resources.
Connection encryption - without a VPN, access to resources goes through the provider. Using a VPN, data passes through the service over an encrypted channel, hiding access to the real IP address

It is on these two pillars that his work rests. By connecting to the country offered from the list, you start surfing the Internet as if being in the country you have chosen. At the same time, your connection goes through an encrypted channel - neither your provider nor the system administrator has access to your browsing history.