What does a paradox mean?
Paradox
A paradox is a statement that, despite apparently valid reasoning from true premises, leads to an apparently-self-contradictory or logically unacceptable conclusion.[1][2] A paradox involves contradictory-yet-interrelated elements that exist simultaneously and persist over time.[3][4][5]
Liar paradox
If "this sentence is false" is true, then the sentence is false, but if the sentence states that it is false, and it is false, then it must be true, and so on.