Tuning is when we change or improve something so that it works or looks better. Imagine you bought an old bicycle and decided to make it cooler: you painted the frame a bright color, installed new wheels, and added a comfortable seat. This is tuning, but for a bicycle.
The Ukrainian equivalent of tuning is “adjustment” or “refinement.” It means the same thing, just sounds more native. Tuning is often associated with cars: when an owner installs new headlights, an audio system, or modifies the engine on their car, that is also an example of tuning. Sometimes people tune their cars to make them more powerful, or just to stand out on the road.