Most small guitar amps have the control section – the part with all the knobs – on the same box as the speaker cabinet. It’s all one single unit. But there are also amps that have a separate “brain” unit that is separate from the speaker cabinet. They connect via a cable that you can plug and unplug, the same way your guitar plugs into the brain. Well, these 2-part amps can be a real advantage when recording. The reason for that is that you can run a long cable between the brain and the speaker cabinet, placing the cab in a more sonically desirable room or space while the player (who is often also the recording engineer in home recording situations), can sit by the computer or other recording console, monitoring the guitar with headphones.
Here is an article that shows you how to do this: