"find local navigation grid path" and "add local navigation grid for box functions"

Hello!
I need help with “find local navigation grid path” and “add local navigation grid for box functions”, so I can work with them
feel free to explain how I can use these functions and where to use them.
I couldn’t find any resources on how to use these functions and the unreal documents don’t provide a solid explanation.

In order to find out, at “find local navigation grid path”, I put 2 points, both in navigation, put the array in “for each loop” then debug sphere node. But the exec pin after the loop wasn’t even played, perhaps the array was empty. what would be the meaning of a node that returns an empty array? Seems it just doesn’t work.