Georeferencing is like putting a sticker on a map that tells you where everything is.
Let's say you have a picture of a map, but there are no labels showing where the cities or countries are. Georeferencing helps you add those labels by matching the picture to a real map with coordinates.
It's like taking a piece of paper and putting it on top of a map to draw the locations. In the same way, georeferencing helps you stick the picture on top of the real map so you can accurately identify the locations that you need to.
This way, you can use the real map to navigate and locate places even if you don't have the original map that you wanted to add labels to.