Hello there.
Tracking means getting the vehicle to move in the right direction, and to reduce tyre wear and improve economy. If tracking is out, your car might wander, pull to one side, wear out tyres etc.
Balancing is mainly done on the rim. Rims and tyres (complete wheel) are rarely 100% balanced, so if this is out of balance, your car might wobble at certain speeds.
If unstable braking is an issue, your brake discs might be warped.