First of all, when you want to ask about the time, you have two options.
Mennyi az idő?
Hány óra van?
These questions are the same and interchangeable, and they both mean 'What's the time?'
When you want to say the hour and the minutes, use 'óra' and 'perc', or just leave 'perc', or just leave anything but the numbers.
12.25 - tizenkettő óra huszonöt perc = tizenkettő óra huszonöt = tizenkettő huszonöt
When it comes to quarter, half or three-quarter, we use the following words: 'negyed', 'fél', and 'háromnegyed'. There is one thing here that is very different from English. When you use 'negyed', 'fél', or 'háromnegyed', you have to say the next hour after them as the next hour has already started - says Hungarian logic. :)
8.15 - negyed kilenc ('quarter nine')
8.30 - fél kilenc ('half nine')
8.45 - háromnegyed kilenc ('three-quarter nine')
Two more things to remember. First, never use 'óra' when you use 'negyed', 'fél', or 'háromnegyed' (so there isn't *'fél kilenc óra'). Second, when the time is expressed in 24-hour format (that is common in Hungary), always switch back to 12-hour when using the phrases above (so 20.30 wouldn't be *'fél huszonegy' but 'fél kilenc').
You can find some exercises on these here and here.