An iambic foot (iamb) has a short syllable followed by a long syllable (SL or U/).
Octameter is eight feet per line.
Upon a nest a bird I saw that had a bracelet in its beak
And, though you won’t believe a word, I heard the bird begin to speak.
It said: “I am the bird of jewels – I steal some new ones ev’ry day.”
Since then my jewels are hid from sight – you’ll never find them on display.
Anonymous – Jeweller’s Lament
A closer look at the feet in this poem
U = short syllable; / = long syllable; | = division between feet
Although “jewels” is two syllables, you can get away with pronouncing it almost as if it’s a single syllable. This could be called cheating – but it works!