This is the 563rd most frequent Hebrew word.
עיריית
The Hebrew word "עיריית" means "municipality" or "city council" in English.
In this usage, 'עיריית' (municipality of) conveys the entity making the decision, attributed to Ramat Gan in this case.
עיריית רמת גן החליטה להקים פארק חדש.
The Ramat Gan municipality decided to establish a new park.
Here, 'עיריית' (municipality of) is again in a possessive form, modifying 'Jerusalem' to indicate the administrative body responsible for the city's activities.
מדי שנה עיריית ירושלים מארגנת פסטיבל לתושבים.
Each year, the Jerusalem municipality organizes a festival for its residents.
In this sentence, 'עיריית' (municipality of) is used in a possessive form to denote the governing body associated with the city it pertains to, here referring to Tel Aviv.