This is the 862nd most frequent Polish word.
zeszłym
"Zeszłym" means "last" or "previous" when referring to time (e.g., last year).
Here, 'zeszłym' refers to a specific time period in the past, namely 'last week'.
W zeszłym tygodniu odwiedziłam swoich dziadków.
Last week, I visited my grandparents.
In this case, 'zeszłym' is used to point to 'last century', indicating a past time frame.
Rozmawialiśmy o wydarzeniach, które miały miejsce w zeszłym wieku.
We talked about events that took place in the last century.
Here, 'zeszłym' relates to 'last year', which situates the event in the previous year.