A project is a way of organizing and attributing API requests. Every project has it's own API Key that you need to use to authenticate each API call.
To create a new project go to Dashboard and click on New project button. This will open a new modal that will allow you to define a name for your project to easily identify it in the list. You can create as many projects as you need.
For example to better organize your integration, you could create two projects one for production and another one for development. Each project will have their own API Key so usage will be attributed accordingly.