When a person, more often than not a woman, shown is behind a backlighted screen of some kind, usually during a conversation with a man. The person is often undressing while doing so.
Expect her to have to bend down, a lot, slowly. Expect also that the screen—which is apparently supposed to ensure some form of modesty—will be as thin as paper and positioned right in front of a source of light, leaving absolutely nothing to the imagination and thus utterly defeating its supposed purpose.
Alternately, she's taking a shower - and stretching, of course - in a shower stall with a frosted-glass door.