What means "Separation" and refers to the division of India in 1947 into 2 countries, India and east and west Pakistan?

Partition is the experience being described.  I would say
that one of the best works to actually read on this topic would be Salman Rushdie's
"Midnight's Children," which recounts the challenges in Partition.  Essentially, when
the British began to realize that their hold on India was slipping, it was involved in a
problem.  After occupying the nation for so long, it had done a good job in repressing
the individual identities and cultural heterogeneity that had defined the people of the
Indian subcontinent.  They realized that the could not simply "leave" and expect "India"
to the be the same nation that they had governed for so long.  At the same time, Indian
politicians began to recognize that as the British left, a void of leadership was
created into which they could easily enter.  The politics of declaring and fighting for
independence for India became vastly different in ruling and controlling it.  In the
end, typical political horse trading ended up creating a Muslim majority in Pakistan and
Bangladesh with the predominant Hindu majority in the new India.  Certainly, as this
solution might have been presented in a simple manner, it was far from simple as the
exact social reality of Partition took a great toll on the new nations being
formed.