So no one freaks out

Crop Factor, Simply Put
When you put a full-frame lens on a smaller sensor camera (like APS-C), it looks like you’re zoomed in. That’s because the smaller sensor “crops” the image.

So, a 50mm lens on an APS-C with a 1.6x crop factor acts like an 80mm in terms of field of view. But the lens itself doesn’t actually change — it’s just the sensor size that’s making it feel tighter.

Important note: this only matters when you're comparing to full-frame. The lens is still 50mm. The “80mm” thing is just how it behaves in comparison.