Next to this text you see the 50mm and 35mm DX. Both lenses are standard lenses voor the FX and de DX. They are cheap. Nice to know is, that both lenses can be uses on both cameras!
With the DX the 35mm will give you the standard view, almost like the human eye. When you would buy a 50mm FX too, then that would be a nice sort of telelens: 75mm, very good for portraits for instance and you would have two very fast lenses, both f1.8.
But.... you can also use de 35mm DX on an FX camera. I know with Nikon the camera switches the FX sensor to a DX one when it detects a DX lens. But you can turn that off in the menu. When you do, you can use the 35mm lens as a wideangle lens. Till up to f8 this gives nice images, tho the corners of the photo are a bit dark. You can solve this in Photoshop with filter / lenscorrection, with which you can remove the vignetting.
When you buy an FX 35mm f1.8 it will cost you a lot of money, while this lens is just as good en far cheaper.
Like they say: If it ain't Dutch, it ain't much.... We always find a way to save us some money :-) Why wouldn't you? Even when you are not Dutch?
If you like to read more about this and see more examples, you could have a look at PhotographyLife. They even compare the 35mm to a real FX lens.
There is more to read on the site of Thomas Fitzgerald. So if you have an FX body and a 35mm DX lying around somewhere.... give it a try.