Maayan

The truth is that this is a common mispronunciation of the name Mayan (2 syllables).
In Hebrew there is a letter (ain) that means than the following vowel should come from the throat. In this name it appears after 'Ma' And before 'Yan', which is a rare case in which it is used without a following vowel. This is probably the reason most people pronounce it as though there was an 'A' after it.
The correct pronunciation would be Ma(throaty pause)Yan.

Maayan is pronounced mah-ah-yahn, with a glottal stop between the double a's to make three syllables.