What phonetics studies
Phonetics is the branch of linguistics that studies the sound side of language: how speech sounds are produced, what elements make up the stream of speech, and how sounds combine into syllables and words. Phonetics describes not the meaning of words but their material, audible form.
The main object of phonetics is the speech sound. A speech sound is the smallest, further indivisible unit of the sounding stream that we pronounce and hear. Sounds form syllables, and syllables form words.
A sound and a letter are not the same
It is important to distinguish a sound from a letter. We pronounce and hear a sound, but we write and see a letter: a letter is merely a written sign for indicating a sound. In a word the number of sounds and the number of letters may differ, and the same sound is sometimes written with different letters.
The word “мактаб” has 6 sounds and 6 letters; but the letter “е” at the start of a word stands for two sounds [ye]: “емоқ” ≈ [yemoq].