Okay, so I've had Krita for a few months now and I'm still very new to art tablets and basically everything to do with art on a computer.

My issue:
Whenever I go to erase something, it erases the blank canvas underneath the stroke I'm trying to get rid of as well.
Is this normal for these programs? Or is there any way to change this?

This is probably a really stupid question, but it's quite annoying and I'd really appreciate any help any of you can give.

In contrast to photoshop or gimp, all krita's layers always have an alpha channel. It's kind of historical baggage: Photoshop and gimp were created back inthe day when one layer and no alpha was the only thing people could have. You can do two things: either don't draw and erase on the first layer (krita by default gives you two layers), or select a non-transparent background color for the whole image. That option is in the create image dialog and in images/properties as well as images/background color.

Thank you so much!