In photography perspective refers to the relationship of objects in a photograph - including relative position, size and space between them. It can be manipulated to create illusions of space and distance, by changing your position, switching lenses, adjusting focal length etc..
With a wide-angle lens
, for example, near objects look very large and far objects look very small, warping our view of the true-to-life relative scale of objects.
Similarly, the same subject captured at difference focal lengths can show how perspective changes.