A rhythm
Poetry is a musical language. One of the greatest characteristics of musical works is that the flow of notes is rhythmic. The so-called rhythm means that strong beat and weak beat cooperate in a certain form and appear regularly and repeatedly. Anyone who knows something about music knows that there are two basic rhythms in music, namely strong-weak (2/4 beat) and strong-weak-weak (3/4 beat). Give a simple example:
The rhythm of children's song Happy New Year is strong-weak-weak;