So basically, if you press Dash for the first time, the Knight will perform Shade Cloak. This ability has 1.5 seconds cooldown that cannot be reset by any means, even by using the Dashmaster charm. Overall, Shade Cloak is indispensable for boss fights in your late game and grants the Knight entry to areas locked by Shade Gate.
This ability will help the Knight penetrate enemies, their projectiles and attacks, as well as the Shade Gates that you could find in Fog Canyon or Ancient Basin. Also, this ability can be upgraded to Shade Cloak. To acquire the Mothwing Cloak, you have to defeat Hornet in Greenpath. However, this ability has a cooldown of 0.6 seconds, which the Knight can reset by taking damage, pogo-jumping, or clinging to a wall. Mothwing Cloak allows the Knight to reach farther areas otherwise unreachable by jumping and makes dodging enemies or simply fleeing from the fight much more effortless. Possessing this ability will make Knight be able to dash towards the direction he is facing.
How to get all Abilities in Hollow Knight: