Are you in the US and a legal permanent resident? Have you been married for less than 2 years? If so, then the foreign national spouse will enter the US on conditional permanent resident status and will come in on a Conditional Resident (CR) Visa, as opposed to and Immediate Relative (IR) Visa. Within 90 days before the 2 year anniversary of your spouse's entry, you and your spouse need to remove the conditions.
To learn more about green cards and conditional residency, you should speak with an immigration attorney.