Ah, I understand.
If you get a USB interface of any kind, it will connect direct to your PC with a USB cable (often supplied with the hardware, if not you can pick one up cheap enough - it's the same lead you'd connect a printer up with for example).
Most audio USB interfaces will have a number of inputs and outputs, depending on how sophisticated thay are.
Depending on your needs, you'll probably want one with a ¼” jack socket to plug your guitar into direct. You might also need a Line Level input to take a feed from an outboard guitar prtocessor or amp with a direct output, and possibly an XLR input for connecting a microphone. If you use a condenser microphone, you might also need a unit with phantom power (usually 48V).
Again, depending on your needs, your USB interface can probably be used as your PC's audio soundcard, so if you intend to use it permanently, you will need to ensure the output options are sufficient. You'll probably need a headphone socket, and maybe also Line Level out sockets (either 2 monos or 1 stereo) so you can either run a pair of powered monitor speakers or feed to a separate amp and speakers.