The command tells your Windows installation, "Stop looking for the default Microsoft activation server, and instead look for the server located at kms8.msguides.com when you try to activate."
While the Software Licensing Management (slmgr) tool itself is a legitimate Microsoft utility for managing licenses, using it to point toward servers like falls into a legal and security grey area. Understanding the Slmgr Command slmgr skms kms8 msguides com
The command slmgr /skms kms8.msguides.com is a powerful administrative tool that illustrates the flexibility of the Windows activation architecture. It specifically reroutes the activation handshake from Microsoft’s official servers to a public server hosted by MSGuides. The command tells your Windows installation, "Stop looking