In Hawaiian, ‘O wai kou inoa? is literally asking "Who is your name?" but of course, in English we say what instead of who. This is simply a distinction made in Hawaiian and other Polynesian languages. Otherwise, wai means who and he aha means what.
'O wai can be used like this as well - He aha ka puke? - What is the book? He puke wehewehe ia. - It is a dictionary. in contrast to - ‘O wai ka puke? - What is (the name of) the book? ‘O "The Grapes of Wrath" ia. - It is The Grapes of Wrath.
Aha refers to things ("what?"). Wai refers to people ("who?"). In a twist that seems odd to English speakers, Hawaiian treats names of people the same way it treats people - so you use "wai" to ask for someone's name. This means that the Hawaiian question "'O wai kona inoa?" would literally translate as "Who is their name?" even though in English we would say, "What is their name?"
Perhaps a more experienced speaker can chime in, but my understanding is that it really mostly effects any vowel in front of it. So at the beginning of a sentence or following a consonant your normal English beginning to the vowel should be fine. But if the word before it ends with a vowel. Make sure to stop all air flow before starting the word with the 'okina.
In English, a glottal stop at the beginning of a vowel-initial utterance is pretty much optional, but 'ai and ai, e.g., do sound different, and one wouldn't say a'ole. It's too bad the missionaries who started writing Hawaiian with latin letters didn't think of using "q" for the glottal stop. As it is, we can't even capitalize that consonant when it starts a sentence. Qaqole.
I might be wrong on this, so I'm looking for feedback. I thought that even in Hawaiian a sentence-initial vowel is always started with a glottal plosive even if there is no 'okina. Does Hawaiian start words that lack a glottal stop with an open glottis? If so, how is this different than words that have an h in front of the vowel? If I am correct that you pronounce all sentence-initial vowels with a glottal plosive, then you cannot actually hear a difference between minimal pairs that only differ by the initial 'okina at the beginning of a sentence.