This is the 773rd most frequent Finnish word.
palvelun
"Palvelun" is the genitive or accusative singular form of "palvelu," meaning "of the service" or "the service" in English.
Here, 'palvelun' is the object of the verb 'käyttivät', in its accusative form indicating the specific service that was used.
He käyttivät palvelun nopeasti ja tehokkaasti.
They used the service quickly and efficiently.
In this sentence, 'palvelun' is in the genitive case, showing possession or association, indicating that the availability pertains to the service.
Palvelun saatavuus on parantunut viime vuosina.
The availability of the service has improved in recent years.
Here 'palvelun' (the genitive form of 'palvelu', meaning 'service') is used to describe what was ordered.