In route summarization what does the term hiding...

Postal system :In the postal system, the core layer is only information which is required to make a routing decision in the city or state information.
We can see some specific street numbers and names hidden because the core layer doesn’t require them.
Telephone system :In a telephone system, at the core layer, the area code is used to make the routing decision.The specific last four digit of the phone numbers are hidden because the core layer doesn’t require them.

In route summarization what does the term hiding information mean?