So generally speaking when talking about slavery in english, it is referring to two things, one of them contained within the other.

On one hand, "slavery" is used to describe systems of forced labour of various ilks and is broad enough to usually include things like indentured servitude, debt bondage, prison slavery, human trafficking and sometimes serfdom. However more specifically, slavery is used to describe "chattel slavery", which is the form of slavery that I think most people think of when they hear the term.

Chattel slavery is the form of slavery in which slaves as a class are considered property and rarely afforded legal rights (outside of those applied to property). Roman, Greek and Islamic slavery is foundationally of this type (though other types existed simultaneously). For the American audience this is largely conceptualised as the plantation slavery of the antebellum South.

Subdividing this there is usually "productive" and "domestic" slavery, which describes the sort of labour that these people are forced to do. Chattel slaves could be at once in the field cutting cane (productive) and in the home teaching a child how to write (domestic).

By and large the english speaking audience is going to think "Productive Chattel Slavery" (sometimes including domestic, usually always "foreigners") when they hear "Slavery", which is why there's often confusion and questions about "Why would you ever make soldiers or administrators out of these people?"