How many prisoners were held in the camps, and what type of work did they perform?

The question about prisoners refers to a specific context that isn't provided in your question. If you are referring to concentration camps during World War II, specifically those run by Nazi Germany, it is estimated that about 6 million Jews were killed in the Holocaust, along with millions of others including Soviet civilians and prisoners of war, Poles, Romani people, the physically and mentally disabled, homosexuals, and political and religious dissidents, bringing the total to as many as 11 million or more individuals.

The types of work performed by prisoners in these camps varied widely. Some were put to work in forced labor for the Nazi war effort, such as in weapons factories or on construction projects like the Atlantic Wall defenses. Others worked in more menial roles, performing maintenance tasks, working in the camp's administrative offices, or being forced to carry out tasks related to the running of the extermination camps themselves, such as Sonderkommando units who were made to operate the crematoria.

In other contexts, such as Soviet Gulags, prisoners were often forced to undertake hard labor in remote regions, for example, mining in Siberia or constructing infrastructure in inhospitable climates.

The conditions in these labor camps were generally appalling, with the labor being physically exhausting and performed in harsh conditions without adequate food, clothing, shelter, or medical care. As a result, many prisoners died from starvation, exposure, disease, and exhaustion.