What you
need depends mostly on what you want to
do. For many people, one guitar is enough. For nearly everyone, one accordion is too many.
You need a sound source, a microphone and mic preamp (if the sound source is acoustic rather than electronic), a recording/playback device, and some way of hearing what you've done. And, of course, cables to connect those things together. That would be the most basic, minimal recording setup.
Wanna record a drum kit? Then you'll need more microphones, a recording device with several inputs, and a mixer.
Need to do justice to a grand piano? You'll need a great-sounding room, a couple of small diaphragm condenser mics, and excellent preamps.
See what I'm getting at? Start small, and grow your gear collection over time.
As your skills improve, you'll discover that different pieces of equipment have different strengths and weaknesses. For example, a mic that sounds fantastic on your voice may sound simply horrible on your blues harp. At that point, you'll realise that you need another mic.
a.