Russian
The tuning is the set of notes available on the instrument. Unlike a piano with its full chromatic range, most kalimbas have a selected, ready-to-use set of notes. These can be easy to combine by ear without knowing music theory.
The tuning determines which melodies you can play. If you do not yet think in terms of notes, think of it as the overall colour or mood. Unless you want to play particular pieces, you can choose intuitively by listening to the sound examples.
You can also change a kalimba's tuning yourself within a limited range, so the initial choice need not be final. ;)