Sure! If you are recording in stereo, you should be able to get the guitar on one side and vocals on the other side. Then, you can split those into separate files if you wish. Or, you can just select the left or right channel before applying any effects, or volume adjustment, etc.
If you want complete isolation, you’ll have to run the guitar direct (without a mic). If it’s an acoustic guitar, directional mics can give you enough separation to so that you can adjust the levels separately. But if there’s a mistake in either track, there will be some leakage and you’ll have to re-record both because some vocal will leak into the guitar mic, and some guitar will leak into the vocal mic.
There are a million ways to do it… But in a pro studio, you’d typically record the guitar first. Then record the vocals while monitoring the guitar with headphones (with vocals mixed-into the headphone mix too.)
Typically, you’ll want to mix the vocal & guitar (at least to some extent) so that your “final product” sounds more natural and is not “hard panned”.* It’s OK to hard-pan some instruments in a multi-track recording, but vocals are usually centered, and it won’t sound right with the guitar on one side and the vocals centered.
What software did your interface come with? Most multi-track DAW software can record each input to a separate file (at the same time). Then, the software will show & play the tracks together so you can pan (move/send left & right) and mix-down to stereo, etc.
One thing you could do is double-track the guitar (record it twice), and hard-pan one track left and the other right. Then, center the vocals.
If you really want to “get into” home recording, read everything you can. Consider a subscription to [u]Recording Magazine[/u], and maybe even look for a book.