To understand word stress, it helps to understand syllables.

Every word is made from syllables.
Each word has one, two, three or more syllables.
word number of syllables
dog dog 1
green green 1
quite quite 1
quiet qui-et 2
orange or-ange 2
table ta-ble 2
expensive ex-pen-sive 3
interesting in-ter-est-ing 4
realistic re-al-is-tic 4
unexceptional un-ex-cep-tion-al 5
Notice that (with a few rare exceptions) every syllable contains at least one vowel (a, e, i, o or u) orvowel sound