For my computer techs, help!

Im not sure exactly where to go for this so I’m hoping maybe someone in this group works or has any knowledge on this.

So I know for a fact my MacBook has a virus & I noticed when I had to update it because I could no longer used my iMovie due to the fact the I needed to update my IOS. (So what it told me) I want to clean/remove the viruses but I don’t know what’s a good app or website to use. I was hoping someone can help me out & refer me either a free or a “need to purchase” app/website.