As with English, there are a number of ways of telling the time in Spanish, depending on whether it's morning or afternoon, or whether you want to say how many minutes are past/before the hour, or if you simply want to give the time numerically. In the latter case, you would say 'es dos trienta y cinco' ('it is two thirty-five').
If you are in Spain, and someone asks you ¿Qué hora es? (What time is it?), you can also answer in the following ways:
It is twenty-five minutes to three - 'son las veinticinco menos tres.'
It is two thirty-five in the morning - 'son las veinticinco menos de la manana.'
It is two thirty-five in afternoon - 'son last veinticinco menos de la tarde.'
It is about two-thirty - 'son las dos y media mas o menos.'
Remembering all this can be difficult, so it's good to get as much help as possible, especially when it comes to pronouncing Spanish words. Watch, and listen carefully, to this film: