I presume you’re talking about synchronizing the lyrics (syncopation is stressing the weak- or off-beat)?
Bingo. I knew something seemed off when I reread the sentence I wrote, thanks. That said I suppose understanding the stressing of words is also pretty important too.
I’ve been using the word phrasing for this concept.
To me it means the way the words and individual syllables line up (or don’t line up) with:
the down and up beats of individual bars (syncopated if emphasis is on the upbeats)
the strumming pattern
chord changes
section changes e.g. verse to chorus
It’s a lot, but all the songs I want to learn do this to a greater or lesser degree.
For me, making my own lead sheets has been key. I put down the guitar, and work out the phrasing on paper or word processor, by counting the beat on 4 fingers and singing.
When I’m confident I’ve got it right, I go back to the guitar and try to practice perfectly from the lead sheet.
Extremely tedious at first, but it works reliably for me. And I find the more I do it, the less I need to do it. The process of making the lead sheets has helped my ear, and the phrasing of new songs comes more easily now.
Has also given me a new appreciation for great song writing!