The “disruptive effect of prior learning on the recall of information” refers to the problem that people can have while trying to learn a new set of skills that are similar to information already known and internalized.
One example of this is the problems that bilingual individuals face when trying to formally study their first language. In this case, a child learns a language at home that is not the dominant language of their environment. Later on in high school or college when they formally study their first language they tend to have a great many problems because the nuances of their dialect like vocabulary, grammar, and accent is frequently at odds with the formal, international standard of the language that the teacher is presenting.
Likewise, if a person has learned to dance, play sports, or play a musical instrument but not been well instructed unlearning bad habits and replacing them with good habits can cause a lot of difficulty.