1. **State the problem:** Find the area of a rectangle composed of square units, arranged in 3 rows and 4 columns. 2. **Formula for area of a rectangle:** $$\text{Area} = \text{length} \times \text{width}$$ 3. **Apply the formula:** Here, length = 4 units (columns), width = 3 units (rows). 4. Calculate the area: $$\text{Area} = 4 \times 3 = 12$$ 5. **Interpretation:** Since each square represents 1 square unit, the total area is 12 square units. **Final answer:** 12