My wife does not have any income. How do I know if she is eligible for a spousal IRA, and if so, how much?

My financial advisor is recommending we fund a spousal IRA, if possible, and she is asking me to ask my tax preparer if my wife is eligible. Since I don't have a person, asking this question above. Is she eligible simply if her income is $0, or are there some more detailed eligibility requirements?