Concept of assonance in figures of speech is a bit hard to understand. Can you please help me with that

Dear Student,
Assonance:

Assonance is the repetition of vowel sounds. For example, there is a repetition of the vowel o sound in the following passage: 

“Poetry is old, ancient, goes back far. It is among the oldest of living things. So old it is that no man knows how and why the first poems came.”

Regards