Not a dumb question if youre just starting out or something, you can plug any bass or guitar into the Amp with a standard instrument cable. But if you want to connect the head to the speaker cabinet then you will need a much thicker speaker cable. It looks similar to am instrument cable but it's different in that the wire is much thicker and can handle much more power which is necessary to protect the amp
My friend was a touring guitar player for more than a decade and he wasn’t aware of this until he switched from a combo amp to a head/cab set up and damaged his new amp by using a cheap instrument cable.