请帮我讲解一下这道题---**Question Stem:** 2. 下图是一块正方形的园地，中间有一个正方形的花坛，周围是草坪。请你计算出草坪的面积是多少平方米。 **Translation of Question Stem:** 2. The image below shows a square garden, with a square flower bed in the middle, surrounded by grass. Please calculate the area of the grass in square meters. **Diagram Description:** * **Type:** Schematic diagram illustrating a square garden with a concentric square flower bed. * **Main Elements:** * An outer square represents the garden. * An inner square is located in the center, representing the flower bed. * The region between the outer square and the inner square is depicted as grass. * The side length of the outer square is labeled as 16m. * The side length of the inner square is labeled as 4m.