What Jinydu's post meant in words is the following:
If we let n be any number (we'll say any real number for sake of simplicity) and define the number X as its reciprocal and say that Y is just renaming the number n then, for example if n=2 then X = 1/2 and Y = 2. Right? The first question posed:
What is the limit as n goes to infinity of X * Y?
is precalc and is asking what is the limit of X times Y (where X and Y are functions of n defined above) as n increases to infinity.
The second question:
Now, what happens if X = 2/n and Y = n and you take the limit?
redefines the function X by putting a 2 on the top and poses the question whether it makes a difference. Same logic goes for replacing that 2 with any constant (real for my explanation of it) number...does it change the limit any?
The overall point was summed together with the statement
the value of "0 * infinity" depends on how the pair of numbers approach 0 and infinity. That's why its called indeterminate
It's just precalc, but if you don't have that under your belt it won't make much sense. I can recommend some decent sources if you feel the urge to delve into it further. Infinity is mentioned often and discussed thoroughly in both calculus (analysis) and set theory.