The first google result defines it as, "the nonphysical part of a person
which is the seat of emotions and character; the soul."
But in different cultures it can mean very different things.
In the Euro-Christian definition, it is thought in a similar way to
the google definition, but it is more-so tied to the human
body, or at least from my experience in the religion.
In Secular terms, it is not certain that this concept can properly
proven or defined.
However in Eastern religions, the soul is not
necessarily tied to the body.
Unlike Christianity, the soul can "reincarnate"
or enter a new body after death.
It does not go to heaven or hell from the start.
The spirit lives on.
Yet in both cases, the soul is immortal,
but goes to different places
depending on who you ask.
Souls can either go to heaven or
hell, or forced to repeat life over
and over... living across different times
until they reach enlightenment.
Depending on who you ask,
I have reincarnated too.
In most eastern religions, it is the process of dying and being reborn
into a new body.
In hinduism, a soul follows a process known as "Samsara"
or the cycle of life, death, and rebirth.
The quality of life depends on one's Karma, or deeds done.
After many cycles of Samsara, once one gains enough Karma,
They can break the cycle of Samsara and their atmun
returns to Brahman
In Bhuddism, it is a bit different
Enough karma will make you reach a certain realm
If attain enough good karma and follow the teachings
of the Bhudda, you will reincarnate
and reach one of the preferred realms.