Well meter is the measurement of rhythm based on syllables and accentuation. Meter is, funnily enough, measured in feet, and every foot is two or three syllables. The names of different meter regarding feet is similar to shapes and their number of sides. For example, a poem where all the lines have three feet or 6/9 syllables is called a trimeter. Accentuation is a bit more complicated but an example of one classification is iambic, which is when the poem can be read consistently by accenting every other syllable, starting with the second. So for a poem that has 6 syllables per line and syllables 2, 4, and 6 are accented, the poem's meter would be classified as an iambic trimeter. That's only one example, you're going to want to look up the other classes of meter but I hope this helped you get introduced to it.
