There are many different traditional forms and conventions and styles for poetry. And infinitely more non-traditional ones.
In simple common English poetry, it’s often the last syllable of each line, which also rhymes.
In iambic pentameter, you have lines of five pairs of syllables, with the second of each pair stressed, and a pause between each line.
Or in heroic meter (e.g. Homer or Virgil) it’s similar to iambic pentameter but was actually dactylic hexameter, e.g.
armA virUMque CAno TROIae PRIma AB orIS.
or…
or…