This is the 1659th most frequent Russian word.
николаевской
"Николаевской" is the genitive or adjectival form of "Николаевская," meaning "of Nikolaevskaya" or "related to Nikolaevskaya," which may refer to a place, person, or thing associated with the name Nikolaevskaya.
The word "николаевской" is an adjective modifying "площади" (square), specifying its association with "Николаевская".
Этот памятник находится на николаевской площади.
This monument is located in Nikolaevskaya Square.
The word "николаевской" serves as an adjective providing information about the gymnasium, indicating that it is named "Николаевская".
Она училась в николаевской гимназии.
She studied at the Nikolaevskaya Gymnasium.
Here, "николаевской" is used to describe the Oblast, indicating its designation as "Николаевская", referring to a specific region or administrative area.