The job board will be one of the primary ways that you are able to make money in the game. Through this you can get jobs like intercepting convoys, fighting off pirates, among other things. As a result, you will make your primary income as a mercenary, doing jobs on the side if you want.
The job board will not be available at the beginning, but will become available at the end of the main storyline. This is because you are technically in the Cat Navy, so you can’t really do jobs on the side.