What is syllable count?
The number of syllables in a lyric line, which determines whether it fits the melodic phrase. Counting is the quickest way to spot a line that reads well on paper but cannot be sung in the space available.
Two lines with the same word count can be wildly different to sing. Checking syllables per line against bars per phrase catches the problem before a singer discovers it at the microphone.
Beats per minute — the speed of the music. Useful for estimating how long a line of lyrics has to be sung, which is how you tell whether a lyric actually fits the melody before the session.
The match between the natural stress of spoken words and the stresses of the melody. Good prosody makes a lyric feel inevitable; bad prosody makes a singer fight the line even when every syllable technically fits.