Kamehameha is, in real life (or rather, was) the first "king" of Hawai'i, having unified all isles under his command. He was best known for not only starting a monarchic rule under Hawai'i, but also because of establishing a law that protects the rights of non-combatants during battle.

But if you want to know the meaning behind Kame-Hame-Ha, it should mean "Turtle Devastation Wave". Kame in Japanese is the term for turtle; an example of that can be seen with FFV's Gilgame, or "Gil Turtle". Thing is, when you mix two words in Japanese, you may end up with a different name, but be warned that it's basically the same; hence, giru (romaji for Gil)+ kame (turtle)= girugame, or Gilgame (gil turtle, or money turtle). The latter are mostly kanji transliterations, which if turned from kanji to hiragana might have a different meaning (much like the kanji for "sword" is transliterated as ken, katana and tsurugi, with the first being the closest to the original Chinese translation of jian). So you might figure by reading the kanji that the name is actually Turtle Wave (or to be precise, its given name, "Turtle Devastation Wave").

But what I really believe Kamehameha is? Pretty overrated, if you ask me so.