What is the relationship between nodes and db hits?

In Graph Academy, the original question is:

What are the airports and flight information for flight number 1016 for airline WN?

The commentary on the proposed query is:

This query required 4382 db hits.

Recall that our dataset only has 100 flights in it. In other words, in order to answer this question, we needed to hit the entire graph twice.

How does the "hit the entire graph twice" fit with 100 flights and 4382 db hits?

Db hits are also counted for reads of properties (one each), relationships, labels etc.
Also for reading indexes or constraints.

db-hits is an abstract unit of work the database has to do.

just comparable between queries