'Qué significa eso?'
You can omit the first question mark, unless you're writing something like a paper, or just want to sound right.
word by word
Qué = 'what'. Keep in mind the 'tilde' on the 'e'. WITH tilde, it's used for a question. WITHOUT, it can be used as an auxiliary word.
'Iré yo, ya que tu no vas' (I will go, as you aren't going). Here the 'que' can't be translated word per word.
significa = 'means'. the stem form is 'significar' (to mean)
eso = 'that'. Used for when you're 'pointing' at something, as to define subject (just for inanimate things though).
Hope this helps :)