This policy setting allows you to force installation of Microsoft Intune Endpoint Protection even if a third party endpoint ...

This policy setting allows you to force installation of Microsoft Intune Endpoint Protection even if a third party endpoint protection application is detected.

"Yes" forces installation of Microsoft Intune Endpoint Protection even if a 3rd party endpoint protection application is installed.
Please Note: If Microsoft Intune Endpoint Protection is installed alongside a 3rd party endpoint protection application, it will run side-by-side with the 3rd party application. Running side-by-side is not recommended because it can interfere with the performance of the client computer.

"No" prevents Microsoft Intune Endpoint Protection from being installed when a third party endpoint protection application is detected.

If this option is set to "No" and a third party endpoint protection application is installed, the Microsoft Intune Endpoint Protection will not be installed regardless of the "Install Endpoint Protection" setting.