What do I do here?

Hint 1 of 5:

This room is optional.

Hint 2 of 5:

There's some bullets on the counter.

Hint 3 of 5:

Those barrels could be covering something.

Hint 4 of 5:

Take the block.

Hint 5 of 5:

After the barrels reveal an opening, you can go in there.