Vocales

a:       The Spanish "a" is pronounced like the "a" in the word "father."

e:        The Spanish "e" is most often pronounced like the "a" in the word "date," except that it is shorter and crisper.

i:     The Spanish "i" is pronounced like the "ee" in the word "see," except that the sound is shorter.

o:        The Spanish "o" is pronounced like the "o" in the word "no," except that the sound is shorter.

u:     The Spanish "u" is pronounced like the "ue" in the word "due," except that the sound is shorter

Source: Vowels Pronunciation