What does the Surah Ar-Rum the 28th ayah means?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his family and companions. I have a question about the 28th ayah of the Surah Ar-Rum. Surah Ar-Rum - 30:28 > He presents to you an example from yourselves. Do you have among those > whom your right hands possess any partners in what We have provided > for you so that you are equal therein [and] would fear them as your > fear of one another [within a partnership]? Thus do We detail the > verses for a people who use reason. I would like to have a better understanding of the verse and its context. What does it mean and whom does it refer to and what is its reason for revelation?