What's the meaning of 'can't spell it'?

He sat down, stared into the fire for a few seconds, and then said, "It begins, I suppose, with -- with a person called -- but it's incredible yeh don't know his name, everyone in our world knows --"
"Who? "
"Well -- I don' like sayin' the name if I can help it. No one does."
"Why not?"
"Gulpin' gargoyles, Harry, people are still scared. Blimey, this is difficult. See, there was this wizard who went... bad. As bad as you could go. Worse. Worse than worse. His name was..."
Hagrid gulped, but no words came out.
"Could you write it down?" Harry suggested.
"Nah -can't spell it. All right -- Voldemort. " Hagrid shuddered. "Don' make me say it again. Anyway, this -- this wizard, about twenty years ago now, started lookin' fer followers. Got 'em, too -- some were afraid, some just wanted a bit o' his power, 'cause he was gettin' himself power, all right. Dark days, Harry. (Harry Potter, book 1)

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Does the highlighted mean (1) I don’t dare spell it for doing so is dreadful or unpleasant,
or (2) I don’t know how to spell the name? Or Both can be possible?
(The reason I wonder is that Hagrid looks up some books for keeping a dragon in the book, and he also was a boy in the Magician’s school. So it would not be quite right to estimate him as an ignorant person.)

I think he says that because he doesn't want to write the word on paper. (But I could be wrong.)

:)

It could be either in theory, but the first is more likely IMO in the context. The person knows the name and is so scared that they will only say it once, so refusing to spell it aloud seems more probable.