"It is evening and it is nine o'clock."
Translation:On ilta ja kello on yhdeksän.
That would sound odd. Finnish uses a mixture of 12- and 24-hour clocks, which is a bit difficult to explain since it's not very precise. In speech 12-hour clock is more common, with exceptions being for example when the exact time down to the minute is important. For example if a train departs at 21.07 (the separator in Finland is a full stop, not a colon), it would be natural to say it kaksikymmentäyksi nolla seitsemän.
When using 12-hour clock the a.m./p.m. type of additions are not normally used. If it's somehow unclear whether the given time is morning or evening, it can be shown by adding aamulla / illalla (morning/evening).