Faceit AC Problem

Hello, i have a problem with FAC, when i try to open it to play the AC shows me a message:
“Error: your system hasn’t been patched against critical Windows security vulnerabilities. Please run Windows Update to keep using FACEIT AC.”
I don’t know what mean “Run Windows Update”, and i guess here i can receive help with this problem.
Thanks for read this. I hope you can help me.
-EP