the.com/port of call

means A stop a ship (or by extension, a traveler) makes along the way to pick up, drop off, or refuel before continuing on.

from Straightforward nautical compounding — 'port' meaning harbor (from Latin portus), and 'call' in the old sense of a ship 'calling' at a place, i.e., stopping there briefly on its route, a usage sailors have applied since at least the 1800s. No hidden trick here: the phrase just names exactly what it describes, a harbor you visit, not the one you're ultimately sailing for.