While you are subjected to the Exhausted condition,
You experience the following effects:

Levels of Exhaustion
This condition is cumulative.
Each time you receive it, you gain 1 level of exhaustion.
You die if your exhaustion level reaches 10.

D20 Rolls Affected
When you make an attack roll, ability check or saving throw,
you subtract your exhaustion level from the d20 roll.

Spell Save DCs Affected
Subtract your exhaustion level from the Spell save DC of any Spell you cast.

Ending the Condition
Finishing a Long Rest removes 1 of your levels of exhaustion.

When you gain a "Well Rested" dice, you can choose to immediately
expend it to remove exhaustion points equal to the dice roll.