The Maya 365-day solar calendar was called the Haabʼ.
The Haabʼ divided the year into 18 periods of 20 days, followed by a short five-day period called Wayebʼ. That makes 360 regular days plus five additional days, for 365 in total. Unlike the modern Gregorian calendar, it did not use a leap-day system to keep the calendar aligned with the slightly longer tropical year.
The Haabʼ was one part of a larger Maya timekeeping system. The 260-day Tzolkʼin ritual calendar worked alongside it; pairing a Haabʼ date with a Tzolkʼin date created a Calendar Round that repeated every 18,980 days, or about 52 solar years. The Long Count served a different purpose by recording elapsed time over much longer periods.
A common mix-up is calling the Haabʼ the Maya “sacred calendar.” That description belongs mainly to the Tzolkʼin, while the Haabʼ was the year-length calendar most closely tied to seasonal and civic time.