What is an indentured servant and what future could they expect in colonial america

Indentured servants were mostly peasants in England which had lost their land in the land redistribution and removal of common land, later they were other people as well.

An indentured servant was a servant that agreed to a person that he/she (mostly men) would work for that person for a certain number of years (I think it was normally 7 years. After that, they were free. They did this later mostly because of the headright system that the Virginia colony had implemented (if you or someone else paid for your passage to Virginia then you automatically get free land[this became a problem later when they ran out of land {bacon's rebellion}]). 

They would and should be free after the amount of time they worked but sometimes they weren't freed because owners could put litigations against them and could keep them for a long time. Also, most of them wanted their land that they were promised but the rich blokes were hogging all of it and they would not let them settle west of the Appalachian mountains.