We are comprised of two components: the physical body and the soul. The soul is the secret of our life. The body is created and the soul is entered into it. Once the soul enters, the different bodily organs start functioning and likewise when the soul is taken away, the body stops functioning.
The Arabic word that is most often used to refer to the soul is ruh, although the word nafs (self) is also sometimes used. The word ruh is also used to refer to the Angel Jibreel and to the Quran, but it is also understood to refer to the human soul.