Plain English Meaning
What you have already learned can help you pick up something new faster, or it can get in the way and make the new thing harder. That carry-over effect is called transfer of learning.
Full Definition
The phenomenon in which previously learned knowledge or skills affect the learning or performance of new knowledge or skills. Transfer is positive when prior learning helps the new task, and negative when prior learning interferes with it.
Context Anchor
Seen in flight instructor training when discussing how a student applies an old skill to a new aircraft, maneuver, procedure, or cockpit situation.
Derivation
From Latin transferre, meaning 'to carry across.' Learning is being 'carried across' from one task or situation to another.