Indonesian letters are the same as those used in English. Historically, the languages of Indonesia had been written in Indian alphabets or the Arabic alphabet. All of the letters A through Z are used, as in English, though some of the letters are pronounced differently. However, unlike English, Indonesian spelling is very consistent: letters are largely pronounced as they are spelled and no letters are silent. You will find that the sounds are similar to Spanish.
Below is a table of the Indonesian alphabet. The pronunciation column shows how each letter is pronounced in Indonesian. The sound column shows how it sounds in English. Where the sound isn't spelled out, it is roughly the same as in English.
Listen to how Indonesians pronounce the alphabet: A-M; N-Z
a (like a in father)
always the a in father, Dali Lama but shorter, never the "a" in catch
be (like bay)
ce (pronounced "chay")
[ʨ] (versus English [ʧ])
Almost always like the ch in church, chest, and in some borrowed words or proper nouns like the French c'est (nearly like English say)
de (like da in day)
like de in deli
[ɛ], [ə], [e] (not [eɪ])
there are three ways of pronouncing e in Indonesian:
one (and by far the more common) is the schwa sound, as in e in stern, learn.
second one is like the e in bed, red.
and third is like in a in foray and came
like the English standalone f, though often substituted with p and vice versa
always the hard g in English: gas, guard except in conjunction with an n
as in the English have except when occurring at the end of a word when it is pronounced but unvoiced
i (pronounced "EE")
Like the long "e" sound in "bee", "see", but shorter
[ʥ] (versus English [ʤ])
like the j in joke, some accents make it sound much heavier making dj a closer transliteration
[k] (versus English [kʰ])
like the k in kite except when at the end of the word when it functions more like a glottal stop
[o] (not [oʊ] or British [əʊ]), [ɔ]
there are two ways of pronouncing o in Indonesian:
like the o in post, rope, but don't pronounce the u sound.