To simplify the expression 4/y + 2 - 3/y - 2 + 12/y^2 - 4, we need to combine the like terms and simplify wherever possible.

First, let's rewrite the expression with like terms together:
(4/y - 3/y) + 2 - 2 + 12/y^2 - 4

Now, combine the like terms:
(1/y) + 2 + 12/y^2 - 4

To add the fractions, we need a common denominator:
(1/y) + 2(y/y) + 12/y^2 - 4(y^2/y^2)
(1/y) + 2y/y + 12/y^2 - 4

Now simplify:
(1/y) + 2 + 12/y^2 - 4
1/y + 2 + 12/y^2 - 4

Therefore, the simplified expression is 1/y + 2 + 12/y^2 - 4.