Incorrect spelling, explanation: this spelling is incorrect because visibility is made from the word visible. Therefore there is an i instead of a. Visible + suffix -ity (noun suffix) is not visability but visibility. There is no need to change that vowel in the middle.

Correct spelling, explanation: visibility is the correct spelling because this noun’s root is an adjective visible. At the same time visability is incorrect, because the root word isn’t visable. There was a noun suffix -ity added and visibility is the correct form.

Definition of visibility:
noun, the degree of how clearly something can be seen
The visibility is poor, drive carefully.
The touch screen is angled for spotless visibility.