I've heard that Mac OS has virus checking

Welcome to the Apple Support Communities.

You cannot. See: macOS - Security - Apple and Protecting against malware in macOS - Apple Support. 

Also, Mac computers do not get viruses. They can only get adware or malware.

Jack

And both the adware and malware have to be downloaded by the user and give it permission. Some simple vigilant computing will prevent that. In over 20 years of using Macs I have never downloaded any adware or other types of malware. Some basic common sense rules are:

• Don't download anything from a site you do not know and trust.
• Never use a torrent for downloading software you did not pay for.