Mak is glossed as enclosed or covered, and it is the thirteenth of the eighteen full months. Landa's account associates the month with a ceremony he calls Tuppkak, involving fire, though the details of his description are compressed and have been read in more than one way.
Where a colonial festival notice is thin the responsible course is to report it as thin. The Relacion survives only in an abridgement made after Landa's death, its month notices vary greatly in length and clarity, and several have no counterpart in any other source. That does not make them worthless, but it does mean a modern reconstruction of a Postclassic ceremony built on one such notice is a reconstruction and should say so.
A Maya date does not name a month and a number in the way a European one does. It names a day in the 260-day Tzolk'in, by number and sign, and a position in the 365-day Haab, by day and month, and the two together form the Calendar Round, which repeats only after 18,980 days, a little under fifty-two years. Within the Haab the days of a month are numbered from zero to nineteen, and the zero day is not called first but seated, the seating of the month, a usage the Classic inscriptions write with its own glyph.