The simplified form of the given expression is:

$1 - \frac{1}{y^2}$

Would you like further clarification on any part of this? Here are some related questions to deepen your understanding:

1. How does simplifying fractions involving variables work?
2. What are common techniques used in fraction simplification?
3. Can you explain how to simplify complex rational expressions?
4. How does factoring help in simplifying expressions?
5. How do you handle undefined values for $y$ in such expressions?

Tip: Always check for restrictions on the variable to avoid division by zero, especially in rational expressions.