The phrase "busy port" means a harbor or dock area where a lot of ships and boats come and go, and there is a lot of activity and movement happening. Full definition
The once busy port had drastically declined as passenger and freight traffic shifted to the railroad. (en.wikipedia.org)
Best known as the world center of movie - making, LA is also a center for shipping (its port and adjacent Long Beach make up the fifth busiest port in the world). (inc.com)
Busy port cities such as Hull come alive with their culture, music and exciting modern architecture, while retaining their distinctive look and feel. (vjv.com)