Incorrect spelling, explanation: sais is incorrect, and says is the correct one because the core verb here is say. Y transforms to i when we add suffix -s in case of a consonant before y. In say there is a vowel before y, so y remains. This way we receive the correct spelling: says.

Correct spelling, explanation: says is the correct form because this is a third person singular form of the verb say in present. In such a case we add s to the end of the word. y only transforms to i when it is preceded by a consonant, but if there is a vowel before it, it remains the same. Therefore sais is incorrect and the correct form is says.

Definition of says:
verb, third person singular of verb say; to pronounce, to express with speech
Jack always says he can’t go out with us. He is an introvert.
The sign says you mustn’t skate here!

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spellingSays or sais