A Virtual Private Network sits between your computer/device and the Internet, it encrypts and anonymizes your connection, making it impossible or very challenging for someone to trace you, view or modify your data. There are many VPN services, some free or very cheap, that promise to not log your internet searching.
Some are probably scams and use shady practices . For good security, you need to learn about it and pay for it.
Some of the best VPN analysis, research and testing has been done by The Wire Cutter . If your serious about a VPN, you need to read their article on why you would use one and which service to use . IVPN is their winner for 2018.
Consider these steps before using a VPN:
On a slightly but not surprising depressing note, the NSA has made major progress on decrypting VPN traffic .