Why SafeHandle's constructor is designed in this way?

below is the pseudocode code of SafeHandle class:

public abstract class SafeHandle : CriticalFinalizerObject, IDisposable {
   // This is the handle to the native resource
   protected IntPtr handle;

   private bool _ownsHandle;

   protected SafeHandle(IntPtr invalidHandleValue, Boolean ownsHandle) { 
       handle = invalidHandleValue;
       if (!ownsHandle)
            GC.SuppressFinalize(this);
   }
   ...
}

I have two questions on SafeHandle:

Q1-Why the first parameter is called "invalidHandleValue" rather than "handleValue"? You use SafeHandle when you need to deal with a native resource, why this native resource is "invalid" in the first place?

Q2-Why there is a boolean _ownsHandle field? when you need to deal with a native resource, you assigns this native resource to SafeHandle's handle field handle = invalidHandleValue;, then this SafeHandle is deemed to have the native resource, so it owns it, how could it possible that it doesn't own the native resource when it has a field that assigned with this native resource?