What is the Good Neighbor Policy?

I have no disagreement with the above answer, but I'd just like to put it in different words in case that would be helpful.

Before Franklin Roosevelt's presidency, the US intervened militarily in Latin America whenever it wanted.  The US sent military units to occupy countries such as Nicaragua and the Dominican Republic when they seemed to the US government to be unstable.  Our "right" to do this was set out in the (Theodore) "Roosevelt Corollary" to the Monroe Doctrine.  This essentially said we had the right to intervene in any Latin American country if we thought it was not being well run.

When FDR became president, he decided that Latin American countries should be left to control their own affairs, even if they seemed to be doing a bad job of it.  This was the Good Neighbor Policy.