A more thorough explanation:

Spes successionis means "hope of succession" in Latin. It refers to the hope of inheriting a right or property, but it is not the same as having a guaranteed right. For example, if someone takes care of their friend for many years, they may hope to inherit their friend's property, but they do not have a legal right to it unless it is specified in a will or other legal document. Spes successionis is different from a contingent right, which is a right that is dependent on certain conditions being met.