Virus issue

There are no known Viruses in the wild that self replicate and affect macOS. There are Malware and Adware that does affect macOS and are often times downloaded as part of an Application from Third Party UnTrusted Site and get installed along with the Application.

Suggest for your peace of mind downloading from a Trusted Developer and Respected ASC Contributor the application Malwarebytes for Mac. It is free or paid for added features. Run the Application and it should remove the malware / adware. Once done, restart computer and test.

I don't know what it is either but it takes more than just clicking some random popup to get yourself into trouble.

There are no viruses that affect macOS, so don't ask for trouble by installing something claiming to fix whatever is wrong. Especially if nothing is wrong.

Other than mistakenly clicking something, is your Mac working properly?