According to the Cambridge Dictionaryhttps://dictionary.cambridge.org/dictionary/english/propagate a definition of propagate is “to send out or spread light or sound waves, movement, etc., or to be sent out or spread”
What it basically means
To spread or to flow
You may hear propagate being used when talking about changing a data structure or the features within a parent component. For instance, a change is said to 'propagate’ through to the child components that are dependent on a feature which is changing higher up in the application
Alternatively, Techopediahttps://www.techopedia.com/definition/23683/software-propagation discusses Software Propagation as modifying existing code and sharing that altered code to other users.