This is the 131st most frequent Latvian word.
pērn
"Last year."
The word "pērn" is used here as an adverb to indicate that the action took place in the previous year.
Pērn mēs apmeklējām skaistas vietas Latvijā.
Last year we visited beautiful places in Latvia.
The word "pērn" specifies the previous year and is complemented by "vasarā" (in the summer) to define the timeframe.
Man ļoti patika, ko mēs darījām pērn vasarā.
I really liked what we did last summer.
The word "pērnā" is an adjectival form of "pērn" and is used here to describe "gada" (year).