There are a few features like Turn Undead which state:
A turned creature [...] also can’t take reactions. For its action, it can use only the Dash action or try to escape from an effect that prevents it from moving. If there’s nowhere to move, the creature can use the Dodge action.
The haste spell states:
Until the spell ends, the target [...] gains an additional action on each of its turns. That action can be used only to take the Attack (one weapon Attack only), Dash, Disengage, Hide, or Use an Object action.
I'm wondering what all "for its action" includes:
Does the Turn Undead feature require to use your "normal action" to take the Dash action? Can you use the action granted by haste instead of your "normal action"? Perhaps Turn Undead requires both of your actions to be used to take the Dash action?
One reason this matters is if you can make multiple attacks with the Attack action, you would want to take the Dash action using your "haste action" and then take the Attack action using your "normal action".
There is already a similar question ("Can you do anything other than dashing while affected by Fear?") where the fear spell only requires that a creature take the Dash action and doing so through any means such as the Rogue's Cunning Action feature or haste qualifies, thus freeing up your "normal action". I'm wondering if this is the same despite the difference in wording.