"Form of Mason"
The name Maysen is commonly a unisex name from the "English" origin.
Maysen is a modern American respelling of Mason, with the first syllable written as May rather than Ma, in the same pattern as the spellings Mayson and Maison. It first appears in United States birth records in 1995, and the records here show it in use for both boys and girls.
Mason means "Stone worker".
The pronunciation of Maysen is MAY-sen.