A person's "sign" is their SUN sign
Sun indicates how we try to like ourselves better. It has nothing to do with our emotions.
If you want to look at someone's jealousy, you need to look at these things in their personal birthchart:
- their Moon sign, since Moon is our automatic emotional reactions, and jealousy is a reaction to inner fear. Look at HOW Moon aspects any of the other 9 planets, because harmonious aspects make it easy to work with emotions, and discordant aspects make it difficult to work with emotions.
- their Venus sign, since Venus is how we relate to others, and jealousy is usually about a relationship fear. Again, first look at HOW Venus is aspected.
- Saturn and its aspects, since a badly-aspected Saturn limits self-esteem, and jealousy at its core is about our fear that we are not lovable and might lose the person.