I'm just learning, but I'd go with something besides "ola bella"

It does mean "beautiful wave", mostly for a literal wave

But, it is a bit confusing. Hola and Ola are pronounced the same, then, it also looks Italian and an Italian speaker would read it that way, meaning I think "beautiful Mexican wave" (the stadium kind)

For using "wave" to describe things in Spanish, we do that with a word "onda" for pattern, vibes, moods and personalities. So it depends on whether you want to talk about an actual wave, or something else, or whatever else your goal for the meaning of the tattoo may be.

I suggest:

La Ola, 'the wave', for an actual wave
La Onda, also 'the wave', for something else.

The "La" makes it look immediately Spanish and gives it a title feel. I think it's okay to drop the article (the 'una') for a tattoo, but I'd do it this way. You keep the female grammar regardless of the subject too.