Serfs were people in the past who were like slaves. They worked for a lord and couldn't leave the land.
Being a serf was not good because they didn't have freedom.
Examples:
The serfs worked in the fields all day.
The lord owned the land and the serfs who worked on it.
The serfs couldn't go anywhere without the lord's permission.
The serfs had to do whatever the lord told them to do.
The serfs had a very hard life with no freedom at all.
The serfs were like slaves, but they worked on farms instead of in houses.