if serfs have to work their whole lives for their lords, what is granted to them in exchange for their services?

Serfs used to get access to the land of the lord to grow crops for their own survival. They were also entitled to justice and protection.

Explanation:

Serfs were the people who belonged to the poorest community of the society. They used to work for the lords. In place of this, they used to get the right to cultivate the land of the lords to grow crops for the lords and for their own subsistence and survival. The serfs were also entitled to protection and justice by the lords.