Your camera has two, or more usually three, types of light meter built in:
- Evaluative/3D Color Matrix meter. You normally use this. This is “smart” metering, where the camera meters areas of the sensor separately. It can handle many types of light situations and is a real improvement on other, older metering types.
- Centre Weighted Average meter. You use this when the subject is in the centre and the outsides are dark or light. Backlight portraits are a good example of where this is useful.
- Spot Meter. You use this when you have great contrast: simply aim the spot at a subject that is neither very dark nor very light and lock your exposure. This is useful when shooting something in a dark room or in a bright snowscape.
Note also that ambient and flash light are metered separately.
My advice: try all three metering modes and get familiar with them, then learn when to use which one.