Do not call that number.
That's a fake so-called Tech Support scam alert/warning which you are seeing in your browser.
"Remember that real error messages from Microsoft, or other big tech companies, never include phone numbers for you to call them.
If your screen suddenly fills with scary pop-ups you should immediately close your browser (try pressing ALT+F4 if you can't do it with your mouse). If you can’t close your browser try restarting your computer."
Also see the other possibilities to get out of such fake browser warnings listed in this reply: Thread "Blocked computer" page 1: AW's reply on January 21, 2023
Suggest reading:
- Protect yourself from online scams and attacks - Microsoft Support
- How to spot a tech support scam - Microsoft Support
To prevent even seeing such fake alerts, use a good content/ad-blocker such as free uBlock Origin.