Question

list = ["Life","The Universe","Everything","Jack","Jill","Life","Jill"]

# Make a copy of the list.
copy = list[:]
# Sort the copy
copy.sort()
prev = copy[0]
del copy[0]

count = 0

# Go through the list searching for a match
while count < len(copy) and copy[count] != prev:
prev = copy[count]
count = count + 1

whats going on

Answer 1

Well, they are experimenting with the things you can do with a list. This will explain all the expressions they used if you're unfamiliar with the terms:
http://www.greenteapress.com/thinkpython/thinkCSpy/html/chap08.html

Answer 2

Not much to be honest. It essentially finds the first ordered duplicate in the list and stores it in the variable "prev".

Answer 3

should i one whole text first ? how to think like a computer scientist

Answer 4

Are you following the syllabus of the class? There are reading suggestions with each lecture.

http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00-introduction-to-computer-science-and-programming-fall-2008/readings/