The king receives tax money, and protects the land, and does taxes. The king is the leader and ruler of a kingdom (s).
The peasants or farmers are workers and farm the land. In return, they get protection. The peasants or farmers, work the lands and provide resources like food for everyone in the kingdom. They also get protection by the knights and church. The nobles are respected for their influence in the church and matters relating to the king. The nobles receive money and do taxes. In return, they back the king and protect the land.
The knights do taxes, fights for the church and protects nobles and their king.The knights are protectors of the church and fight for their king.