How does Array#sort work when a block is passed?

Question

I am having a problem understanding how array.sort{ |x,y| block } works exactly, hence how to use it?

An example from Ruby documentation:

Answer 1

Some miscellaneous points:

• x and y are called block parameters. The sort method basically says "I'll give you x and y, you determine whether x or y should come first, and I'll look after the boring stuff with regards to sorting"
• <=> is called a spaceship operator.