Ok kiddo, so the Bailo of Constantinople is like a really fancy ambassador from another country who goes to Constantinople, which is now called Istanbul in Turkey.
Back in the olden days, there were different powerful people running different countries and they would send these ambassadors to other countries to talk to their leaders and make sure everyone was getting along.
So, the Bailo of Constantinople was basically the fancy ambassador from Venice, which is a city in a country called Italy. They would go to Constantinople to talk to the emperor who was in charge of the Byzantine Empire, which was like a really big and important empire that ruled a lot of places around the Mediterranean sea.
The Bailo of Constantinople would talk to the emperor about really important things like trade and diplomacy and he would wear really fancy clothes to show how important he was.
So, to sum it up, the Bailo of Constantinople was like a fancy ambassador from Venice who would meet with the emperor of the Byzantine Empire to talk about important things.