Having different accounts on a shared PC lets multiple people use the same device, all while giving everyone their own sign-in info, plus access to their own files, browser favorites, and desktop settings.
When a user signs in to Windows, the system loads their profile. Because each user has a unique user account, this allows multiple users to share a computer. When a user signs in, the desktop settings, files, favorites, and history they see are theirs; they cannot be accessed by other users. When that user signs out, their profile is preserved for the next time that they sign in.
This tutorial will show you how to sign in to Windows 11 with your account.