Short answers, pulled from the story.
Metre refers to the basic rhythmic structure of a verse or lines in verse determined by the arrangement of stressed and unstressed syllables. Most Western poetry relies on patterns where certain syllables are emphasized at regular intervals.
The earliest known unambiguously metrical texts date to the Late Bronze Age Rigveda hymns. These Sanskrit compositions represent the oldest surviving examples of structured verse.
English iambic pentameter places a stress on every even-numbered syllable within a ten-syllable line. Five iambs make up this form found in Shakespeare's plays and Milton's Paradise Lost.
Classical Latin and Greek measured syllable weight based on duration rather than emphasis because they ignored word stress entirely. A long syllable contained a vowel that took longer to pronounce or was followed by two consonants while short syllables were quick and light.
Classical Arabic prosody relies on sixteen established metres derived by Al-Farahidi between 718 and 786 CE. Each verse consists of metrical feet combining long and short syllables.