of the tenth (hour; used for times around nine), on the tenth
Маме стало плохо в поезде, и они вернулись домой десятого.
Mom became ill on the train, so they returned home on the tenth.
— Токийская повесть (1953)
It's quarter past nine.
Сейчас четверть десятого утра.
It’s quarter past nine in the morning.
Breakfast is at half past nine.