Resetting lets you choose whether to keep your files or remove them, and then reinstall Windows 10. This tutorial will walk through how to remove all personal settings, applications and settings and restore Windows 10 to a factory (default) state.
Guide to determining what type of reset to be performed (courtesy of Microsoft):
Keep my files
Reinstalls Windows 10 and keeps your personal files.
Removes apps and drivers you installed.
Removes changes you made to settings.