Both. Just on different conditions.
A surfer needs waves. A kitesurfer needs wind. But neither statement is as simple as it sounds.
A beach can have waves and still be unsuitable for a beginner surfer because of their size, shape, currents, tide or the nature of the break.
Similarly, a kite spot can have wind and still be unsuitable for a beginner because it is too strong, gusty or offshore, or because the launch, water state or surrounding hazards are inappropriate.
Progress in both sports therefore depends partly on getting
the right conditions for your level, not simply having waves or wind.
This becomes especially important when planning trips. A surf trip is built around swell seasons and suitable breaks. A kite trip is built around wind seasons and suitable spots.
That's why destinations such as
Northeast Brazil can produce very different kinds of kite trips from places with shorter or more variable wind windows.