Okay, so a really long time ago, there was a group of people called the Portuguese. They were really good at exploring and finding new places to visit and trade with. As they explored, they found new lands that belonged to them and they wanted to make sure they could keep them safe and protected.
To do this, they created something called captaincies. A captaincy was like a small area of land that was governed by a captain. The captain was like the boss of that area and helped keep things in order and make sure everything was safe.
The captaincies were kind of like puzzle pieces that fit together to make up the land that belonged to the Portuguese. Each captaincy had its own captain, but they all worked together to protect and maintain the larger territory of the Portuguese Empire.
Eventually, as time passed, the Portuguese Empire started to lose some of its power and the captaincies didn't serve as big of a role as they used to. But for a long time, they were really important in helping the Portuguese keep their lands safe and protected.