Question

Wild men who caught and sang the sun in flight, The meter, if any, from this line is

Answer 1

This line from Do Not Go Gentle into That Good Night is written in iambic pentameter.
An iamb is a foot (rhythmic unit) of two syllables; the first one being unstressed and the second one stressed. Penta = 5. This means that, in this line, we have 5 sets of iambic feet, which should read like this (lowercase unstressed, capital letters stressed):

wild MEN who CAUGHT and SANG the SUN in FLIGHT.

This pattern is also supported and used throughout the whole poem.