This is the 108th most frequent Spanish word.
zona
An area or region.
Here 'zona' is used to describe a geographic area, referring to a specific portion of the city.
La zona sur de la ciudad es muy tranquila.
The southern zone of the city is very calm.
'Zona' in this context indicates a designated area within the park where specific activities are permitted.
En esta zona del parque se permite hacer picnics.
In this area of the park, picnics are allowed.
In this sentence, 'zona' is used metaphorically to describe a conceptual area representing a state of familiarity and lack of challenge.