This is the 6439th most frequent Russian word.
электропоезда
"Electric trains."
Here, the word is used as the plural subject of the sentence to denote the type of transport.
Электропоезда доставляют пассажиров в городской центр.
Electric trains transport passengers to the city center.
In this sentence, the word is used in the genitive case to describe possession or connection.
Мне нравится скорость электропоезда, на котором я ехал.
I like the speed of the electric train I was on.
Here, the word serves as the object of the verb, indicating what the action is directed towards.