This piece is called the driver side motor mount bracket. It bolts on the upper timing belt side of the block. The bracket allows the driver side motor mount to attach to the engine.
When doing a 6 bolt swap in a 2G, you need to remove this 1G bracket and replace it with the 2G bracket so you can attach the 2G driver side motor mount to the engine. When using a 2G motor mount bracket, you need to grind a notch in the bracket. Otherwise, it will hit the water pump.