When watching films there is a huge amount to observe and learn by studying how the camera is used.  The first area of learning should be about shot size.  Learn about that here

Why is the camera where it is in this photograph opposite?  The filmmakers have made a deliberate and aesthetic choice, referencing knowledge of how a camera is used to shoot snooker on television.

There are many technical aspects to the camera including the physics of light but few of these aspects are essential to the basic use of the camera.  With enough light, cameras on mobile phones can produce an image comparable to that of professional equipment.  Far more important than technical knowledge, is an understanding of how the camera frames and presents the subject.  Here again are some questions to consider when pausing a film to study what is in a frame:

i) What can be seen in the frame & why?
ii) What camera movement is happening & why?
iii) What height or angle is the camera at & why?
iv) What might be excluded from the frame?
v) If the camera is the narrator, what is it saying?
vi) Is all of the frame in focus? If not, why not?
vii) In what ways is our optical (eye/brain) system similar or different from a film camera?