This is the 4386th most frequent Polish word.
hulajnogi
"Scooters."
In this sentence, 'hulajnogi' is used as the subject of the sentence, referring to scooters in general.
Hulajnogi są popularnym środkiem transportu w mieście.
Scooters are a popular means of transportation in the city.
Here, 'hulajnogach' is the locative plural form of the word, used as a specification of the place where the action occurs.
Dzieci zwinnie jeżdżą na hulajnogach po parku.
Children ride skillfully on scooters around the park.
In this example, 'hulajnogi' appears as the plural accusative case, indicating the direct object of the action.