Poetic meter or metre:
Metrical foot: the basic unit of verse meter consisting of any of various fixed combinations or groups of stressed and unstressed or long and short syllables.
iamb: short long: a metrical foot consisting of one short syllable followed by one long syllable, or of one unstressed syllable followed by a stressed syllable (a-bove, de-stroy)
Example of iambic pentameter: If music be the food of love, play on! (Shakespeare, Twelfth Night)
trochee: the opposite: long short (Rich-ard, Ma-ry had a lit-tle lamb, top-sy)
anapest: short short long: a metrical foot consisting of two short syllables followed by one long syllable, or of two unstressed syllables followed by a stressed syllable (un-con-firmed, and a fab-u-lous time, and in-ter-vene).
dactyl: the opposite: long short short (ten-der-ly, mer-ri-ly).
spondee: long long (mid-term, a-men)
pyrrhic: short short (the sea | son of | mists)
tribrach: short short short

The versification of Romance languages is primarily syllable-timed, i.e., based on the number of syllables in each line. Verses are found with any number of syllables from two (exceptionally) to twelve…
In modern French, which has no phonemic stress, the favorite longer verse is the twelve-syllable or Alexandrine, with the possibility of a caesura after the fourth, sixth, or eighth syllable and of subdivisions within a six -syllable sequence, thus forming a very flexible type of line.” from “Prosody,” in the New Harvard Dictionary of Music, p662.
See:  listening arts website

Notes:
Caesura – (in Greek and Latin verse) a break between words within a metrical foot – (in modern verse) a pause near the middle of a line. A caesura is a strong pause within a line, and is often found alongside enjambment. If all the pauses in the sense of the poem were to occur at the line breaks, this could become dull; moving the pauses so they occur within the line creates a musical interest. A caesura may be marked like this: ||
Enjambment is the continuation of a sentence or clause over a line-break. If a poet allows all the sentences of a poem to end in the same place as regular line-breaks, a kind of deadening can happen in the ear, and in the brain too, as all the thoughts can end up being the same length. Enjambment is one way of creating audible interest; others include caesurae, or having variable line-lengths. – See more at the poetry archive
Alexandrine: An alexandrine (French pronunciation: ​[alɛksɑ̃dʁin]) is a line of poetic meter comprising 12 syllables. Alexandrines are common in the German literature of the Baroque period and in French poetry of the early modern and modern periods. Drama in English often used alexandrines before Marlowe and Shakespeare, by whom it was supplanted by iambic pentameter (5-foot verse). .