Wayeb is a period of five days additional to the 18 months of Maya calendar (360 days), said to be dangerous and detrimental to the people, usually staying home and avoiding any activity at risk during this time.
The Tzolkin consisted of 20 periods each with 13 days for a 260-day count. Day names - 01: Imix, 02: Ik’, 03: Akʼbʼal, 04: K’an, 05: Chikchan…. The word tzolkʼin means "division of days”.
“Each day had a number and a name, the numbers from 1 to 13 and 20 day names. When the 13 numbers were gone through, they began again, and the 20 day names continued. When the day names were gone through, they repeated, and the numbers continued up to 13. The cycles of 13 and 20 repeated until they came back to the first number, first name again in 260 days. The priests who kept the calendars used the Tzolkin to determine days for sowing and harvest, military triumphs, religious ceremonies and divination.” (historyonthenet.com)