As wolf, Link has a cooldown on his dashing ability. For most of the length of a dash, if the dash is interrupted, the player must wait out the cooldown timer to dash again. However, the cooldown gets reset if a dash is canceled within 10 frames of it beginning, allowing Link to immediately dash again. It can be faster to intentionally dash cancel in situations where Link's dash would otherwise be interrupted in such a way that there would be a period where dashing is impossible due to the cooldown.
Dashes can be canceled by stopping the dash animation before it is finished. There are two useful ways to do this:
Right after pressing A, press B to cancel the dash. Wolf Link will make the attack animation forward and then be able to immediately dash again.
This can be used in Castle Town, for example, where it is faster to constantly dash cancel instead of pressing A to dash every few seconds.
The second method of dash canceling requires a ledge to jump off. If you press A to dash right before a ledge, the animation of Wolf Link jumping off will cancel the dash and allow him to immediately dash again.
This is used in a lot of places, such as Castle Sewers and while completing Eldin Twilight.
This method is also applicable to the transition between water and land. You can cancel the dash by initiating it right before the transition, which will interrupt the animation and allow an immediate second dash.