Quick answer
Что э́то зна́чит?
shto éto znáchit — the question that unlocks every other word
The options
The stress question is the useful one
Asking Где ударе́ние? surprises Russians and gets you the one piece of information no dictionary in a shop window will show. It is the single most useful question a learner can ask.
What you hear back
Typical mistakes
Что зна́чит э́то сло́во? — with heavy stress on э́то
Что зна́чит э́то сло́во?
Fine as it is — just do not stress э́то, or you sound suspicious of the word.
Как ты пи́шешь э́то?
Как э́то пи́шется?
The reflexive form asks how the word is spelled in general.
Check yourself
How do you ask where the stress falls?