This is the 1732nd most frequent Polish word.
strefa
Zone.
Here, 'strefa' refers to a designated zone or area for a specific purpose (quiet) within a building.
Strefa ciszy jest na drugim piętrze biblioteki.
The quiet zone is on the second floor of the library.
In this sentence, 'strefa' is used to denote a region classified for particular economical activities or regulations.
Strefa ekonomiczna przyciąga wielu inwestorów.
The economic zone attracts many investors.
Here, 'strefa' describes a conceptual zone defining a particular standard of time, specific to geographical regions.