The term "sign gifts" refers to spiritual gifts that are used as a sign or confirmation of God's presence and activity in someone's life. These gifts can include abilities such as speaking in tongues, prophecy, healing, miracles, and discernment of spirits. The idea is that these gifts serve as a visible indication of the Holy Spirit's work within an individual or community. They are seen as a sign of God's favor and blessing, and can be used to encourage and strengthen believers in their faith.