Hi KJSee,
Good day! This is Jhakesong an Independent Advisor and I will be happy to assist you with this.
Those are Advertisements. They would make you think that your computer is affected by a virus and they pretend they are from Microsoft. Once you call the number, they will offer their service and charge you for it. To be sure, run a virus scan using malwarebytes:
In the future, to keep you protected, make sure you always update your antivirus software. Or if you just use Windows defender, keep it updated along with windows updates.
Let me know how it goes. Have a great day!