Many boards are automatically recognized by Arduino IDE-these boards will have their name displayed next to their port in the Tools > Port menu and will have their port associated with the identified board in the board selector menu. The port selection refers to an actual board (or other device) that’s connected to your computer.
In some cases, it will be automatically set, but it can be overridden with the Tools > Board menu or in the “Select other board and port…” dialog. It’s useful to understand the difference between board and port selections: Learn how to select the right board and port in Arduino IDE.