Heaven, Paradise, or refers to a place meant for angels and souls with goods deeds who also believe in God. Needless to say, it is beyond the earthly realm.
Thus, it is believed that when a person dies, he leaves the physical body and his soul descends to Heaven based on his merit.
With Heaven, there has got to be its counterpart, that is, Hell which is meant for Satan and souls with bad deeds who do not believe in God or His authority. Hence, souls that are not fit to be transferred to Heaven are sent to Hell.