The first step of understanding the poetics used in Gurbani would be to understanding the different between laghu (short) and dhīragh/gurū (long) syllables.
View this video to see how a couplet (doha/dohra) is formed with this understanding:
![](https://www.youtube.com/watch?v=M06oVAv5UbY)
Unfortunately there are no English texts which help explore poetic meters in Gurbani. If you know the Hindi script you can use:
Rupert Snell, A Braj Bhasha Reader: https://hindiurduflagship.org/resources/learning-teaching/braj-bhasha-reader/
Otherwise Kahn Singh Nabha's Gurchand Divakar is the best resource:
https://archive.org/details/gur-chand-divakar