Obviously, you have to know the time in English first. Then you have to know the numbers in Spanish. The easy pronunciations are included next to the word.
1 = uno (oo-no)
2 = dos (dose)
3 = tres (trace)
4 = cuatro (qua-tro)
5 = cinco (seen-koh)
6 = seis (says)
7 = siete (see-ay-tay)
8 = ocho (oh-cho)
9 = nueve (new-way-vay)
10 = diez (dee-ays)
11 = once (own-say)
12 = doce (do-say)
To add the words such as 20 or 30 to those numbers, add these prefixes.
20 = veinte
30 = treinta
40 = cuarenta
50 = cincuenta
Next combine these words. For example, if you want to say the number 37, you combine them as treinta y siete. The "y" (pronounced "ee") means "and," which literally translates to 30 and seven.
If someone asks you "Que hora es?" you are ready to answer. If the time is 11:43, your answer is, "Son las once cuarenta y tres," which means, "It is 11:43." If the time is 1:00, you say, "Es la uno." When the number your time starts with is higher than one, you start your sentence with "Son las"; when it is one you use "Es la."
During the second half of the hour, you also can subtract the number of minutes until the next hour when giving the time. For example, if it is 4:45, you can say, "Son las cinco menos cuarto" to state that it's 15 minutes before 5. If it is 5:55, you can say, "Son las seis menos cinco" to state that it is five minutes before 6, and so on.