Virus warnings

Please check Safari Settings or Preferences and select the Website section, then scroll down to Notifications, as shown in the screenshot below. Delete all you haven't knowingly added. or all of them.

Do you have an application called "Memo Premium" installed? Or perhaps "Memo"? It looks to me as if an application is nagging you to upgrade to a paid service and that the offer expires in three days. If that's the case, the pop-up may stop. Or, they may keep nagging you. I'd get rid of the application unless it's something you really need.

None of the notifications on the right side of the display are real either. No one, not even Apple, can "see" what is on your computer unless you specifically give them permission for remote access.

The notifications are likely a separate issue from the "Memo" thing. They suggest you have caught a case of adware, which usually happens when using unscrupulous download hosting sites that offer stuff "free" that you know shoul cost money elsewhere.

Adware can be manually managed but is tedious. The one tool most of the senior contributors here recommend is MalwareBytes, developed by a respected contributor here. To avoid more adware, get MalwareBytes ONLY from the developer's site:

https://www.malwarebytes.com/mac

The free version is run manually when you suspect an adware incursion. The pay-for version runs in the background providing real-time intercepts of incoming adware.