The Maya are Monotheistic.
The Maya believe in a single deity with multiple expressions. These expressions can also be referred to as descriptions or personalities. They can be applied to days, months, and much more. This is no different from a Westerner thinking of Sunday as a day of rest. "A day of rest" is a description / personality many apply to Sunday. Much in the same way, the Maya have applied descriptions / personalities to individual days, and much like Sunday repeats in a cycle, these days also repeat in cycles. There are possibly 17 or more different Mayan Calendric Systems. Mayan Calendar is actually composed of multiple calendars depending on what you are contemplating. For reference there is a Maya Haab Calendar, a Maya Long Count Calendar, the Calendar Round , the sacred Maya Tzolkin calendar, and other calendars recording the progression of the moon, Venus, Saturn and Jupiter (819 day revolution), and more.