This is the 716th most frequent Russian word.
мер
Mayor.
Here, 'Мэр' means 'mayor', describing a person in charge of a city's administration.
Мэр города открыл новый парк.
The mayor of the city opened a new park.
In this sentence, 'мер' is the genitive plural of 'мера', meaning 'measures' or 'actions' to address a situation.
Для достижения наших целей необходимо принять ряд мер.
To achieve our goals, it is necessary to take a number of measures.
Here, 'мер' is again the genitive plural of 'мера', used to denote actions or steps taken as precautions in this context.