Is _Validate on Client or Server?

Somewhere I red that the _validate functions are called locally. If yes, what are they supposed to do? I thought, the Validate functions were to compare the local clients data with the data on the server to see if the client may cheated?

And how do I set a owner in an RPC call? The server spawns the object but the player who send the request should be the owner so that he later on can send RPC calls from this object?

To the second question: I don’t actually know why this works, but it does. Calling SetOwner(this) in the Implementation function where I spawn the objet works,

But the first question remains