(A)An eye for an eye - revenge, believing doing something back to someone who has wronged you in some way as the way forward e.g if someone kicks you, it's only fair you kick them back. If a country bombs you, you bomb them back. If a religion kills some of 'your' people, you kill them back. If someone takes your eye, you take theirs...
Makes the whole world blind - this is the important bit of the statement. You are left blind because you are so consumed in hatred and revenge for someone who has wronged you, you cannot SEE the only way out is to forgive/break away/etc... so you are just left in a constant circle (as someone has to see there is no way forward, that's the play on words, no can SEE that, as they are BLINDED...)
that's the metaphorical explanation for it...
(B)An eye for an eye refers to vengence, and it's reference is loosely taken from the Bible, you take my eye, I'll take your eye, you take my tooth, you get the picture. While people use this as justification for vengence, scripture teaches vengence is Mine referring to the Lord, but that's another question.
When Ghandi said this he was living in a very vengeful, hate filled troubled time and he was trying to focus people in a different direction. One of the ways he did that was to point out the irony of the mentality that thinks first of vengence and not of forgiveness.
If every body gets even, after a while there won't be any one.
If we all take an eye for every eye we lose, pretty soon we can't see at all.
Vengence makes losers of us all ….
2.First the meaning means if you think about it an eye for an eye in itself is a meaning for revenge. The last part Makes the whole world blind just helps elaborate that as revenge is so constant and happens so much it makes the world blind.