Quick Answer
If 16 oz means US fluid ounces, it equals approximately 2 cups.
If 16 oz means ounces by weight, the answer depends on the ingredient. For example, 16 ounces by weight is about 3.63 cups of all-purpose flour, 2.27 cups of granulated sugar, and 2 cups of butter.
The first step is always to confirm whether the recipe means fluid ounces or weight ounces.