The meaning of the word Disposses is to deprive someone of land, property, or other possessions.
For example if you did not pay your real estate taxes and then the county sells off your house or property for the back taxes owed then you would be dispossessed of that property or house.
It basically means the same thing as taking someone away from you forcefully that you possess.
If you possess something which means you own something then someone takes that away from you legally and forcefully then they are dispossessing you of the property.
The word disposses also means to to put out of possession or occupancy.
It can be similar to being evicted forcefully or you were forced out of your home due to foreclosure then you would be dispossessed of that property.