To block you will have to press L1 / left bumper to bring up a spiritual shield, which will block most of the attack, although it will still take a little bit of health. But you can avoid the loss by timing the blocks to get a perfect one. So you'll have to run the block when an attack lands.
That's all you need to know about how to block in Ghostwire Tokyo, so now that we've reached the end, we hope you'll master blocking in the game now that it's coming out.