He was talking about the SM58, but many mics require an audio interface. Basically you need to use a USB connection to connect to a computer, and some mics do have a USB connection, but most professional quality musician microphones use XLR cables. An audio interface is basically a little hub that you plug your XLR cables from your microphone into (or 1/4" cables which are also common but are mostly for other instruments) and the audio interface itself connects to the computer with USB and sends the audio into the PC

Like someone else said, a really high quality, professional, and relatively cheap setup would be a Shure SM58 microphone and a Focusrite Scarlett 2i2 audio interface. In fact I'm a home studio musician and this is very close to my own setup