Backlighting does not automatically mean incorrect exposure. It initially means that much of the light comes from behind the subject. For a person in front of a window, the camera sees a mixture of bright exterior and darker face. Depending on how it weights those areas, you may get a bright window with a dark person or a readable face against a very bright background.
Assess the face first
Begin with your usual multi-area metering and a test frame. If the face is too dark, increase exposure compensation gradually. Watch bright skin areas rather than only the overall impression. The meter may already respond to a detected face, making a blanket correction of several stops unnecessary. Also check that the camera has actually recognized the intended person.
Spot metering can give the face more weight, but it is not an automatic skin-tone reader. It tries to reproduce the measured area at a particular middle brightness. Very light and very dark skin therefore still need deliberate judgement. Depending on the model, the metering spot is central or follows the active focus point. Do not assume the focus box also marks the metered area without checking.
When the brightness gap remains too large
No metering method can simultaneously add missing light to the face and darken the exterior. If both matter, change the situation. Turn the person slightly towards the window so light reaches the face from the side, or frame less of the bright exterior. A pale wall opposite the window can bounce natural light back. A reflector needs a position that actually directs light onto the shadow side.
If the window is intended as a white background, losing its detail may be acceptable. That deliberate choice is more useful than trying to preserve every tone at any cost. In a documentary interior photograph, however, the view outside may be essential. Another time of day with a smaller brightness difference can then help more than additional compensation on the dial. When light enters the lens directly, also watch for veiling flare and reflections: a small sideways change in viewpoint can improve contrast without altering exposure.
