A description of the SLR.
There are various types of camera though, I’m. And I think thing is once you have heard “DSLR” camera know what?
Mirror is turned into the camera, camera here reflected the light of the views of the light came in from a lens outside of Finder toward views from the Finder looks. Lens with only one camera. To say things that reflect the “reflex” in English, for brevity referred to as DSLR.