The word jikan (時間) means both time and hour. To tell the time in Japanese you use counters. Counters are words that often by themselves have no meaning, but they get attached to a number and are used to count the number of something.
Useing counters to count is like using the English sentences 1 load of laundry, 3 spoonfuls of sugar except in Japanese counters can be used for almost everything they count. Below are counters that are time related.
Hour = ji (時)
Minute = fun/pun/bun (分)
Some Japanese numbers have more than one way of saying them, however there is only one way to say each Japanese number when speaking about time. The numbers that follow a special pattern are underlined.
To specify if it is AM or PM the system is a little bit different from western methods. Gozen (午前) means before noon. gogo (午後) means afternoon. You can place the appropriate word before the number.
It's 7 afternoon = gogo shichiji desu (午後7時です)
It's 3 before noon = gozen sanji desu (午前3時です)
It's 11 afternoon = gogo juuichiji desu (午後11時です)
When telling the minutes in time you say either fun or pun depending on the sound that comes before it.
To tell the time first you put the hours and then minutes. When you get to 10分 it can be pronounced either jippun or juppun.
It's 2:15 = niji juu gofun desu (２時１５分です)
It's 2:30 = niji sanjippun desu (２時３０分です)
It's 2:45 = niji yonjuu gofun desu (２時４５分です)
It's 2:35 = niji sanjuu gofun desu (２時３５分です)
If you need to say it is half past something you use the word han (半) which means half.
It's half past two = niji han desu (2時半です)
It's half past five = goji han desu (5時半です)
It's half past ten = juuji han desu (10時半です)
When you want to ask what time is it in Japanese you can say any of the following sentences depending on if you are speaking casually or polite.
What time is it? = nanji desu ka (何時ですか)
Now, what time is it? = ima nanji desu ka (今何時ですか)
Now, what time (is it?) = ima nanji? (今何時？)