Are Saving Throws Ability Checks

Is a saving throw an ability check hex?

The hex spell affects ability checks, not saving throws.

What is the ability for saving throw?

To make a saving throw, roll a d20 and add the appropriate ability modifier. For example, you use your Dexterity modifier for a Dexterity saving throw. A saving throw can be modified by a situational bonus or penalty and can be affected by advantage and disadvantage, as determined by the GM.