A more thorough explanation:

A sea rover is a person who travels on the sea to steal things from other ships. They are also known as pirates. A sea rover can also refer to the ship that the pirates use.

• Blackbeard was a famous sea rover who terrorized ships in the Caribbean.
• The sea rover's ship was equipped with cannons and a crew of fierce pirates.

The examples illustrate how sea rovers were pirates who sailed on ships to steal from other ships. Blackbeard was a well-known sea rover who was feared by many sailors. The second example shows that the sea rover's ship was designed for battle with cannons and a crew of fierce pirates.