the better part of a year & full holiday season

[Eway]

Dear Teachers,

When people say "the better part of a year", such as "they worked around the clock for the better part of a year", what time of a year does that mean? And, what is a so-called "full holiday season"? A national holiday?

[konungursvia]

The better part just means the larger part, or more than 50% of the year. I don't know what they mean by the second phrase.