During combat, you should see the Spider Senses animation appear above Spider-Man’s head as an enemy begins their attack.
Once you spot the Spider Senses animation, press the L1 button in order to parry. Note that you can’t parry gunfire or any attacks that cause your Spider Senses to turn blue. Meanwhile, attacks signified by yellow Spider Senses can’t be dodged and must be parried.
Pressing L1 early will reduce the damage taken, but will not cause the enemy to stagger. In order to do this, you’ll need to press L1 just before an enemy’s attack lands, which will be signified by the Spider Senses icon turning red. When successfully executing a parry, an animation will trigger – by default, Spider-Man will use his robotic arms to parry, while Miles will use a blast of electricity. These animations will change depending on what abilities you have equipped, with Peter unlocking Venom variations later in the game.