This policy setting prevents the user's machine from launching Microsoft .NET Framework setup when navigating to .NET Framework ...

This policy setting prevents the user's machine from launching Microsoft .NET Framework setup when navigating to .NET Framework content in Internet Explorer. Microsoft .NET Framework is the next generation platform for Windows, utilizing the Common Language Runtime and incorporating support from a number of developer tools. It includes the new managed code APIs for Windows. 

If you enable this policy setting, .NET Framework setup will be disabled. Users will not be able to change this behavior.

If you disable this policy setting, .NET Framework setup will be enabled. Users will not be able to change this behavior.

If you do not configure this policy setting, .NET Framework setup will be enabled by default. Users will have the freedom to change this behavior.