Area is how many unit squares can fit in a figure. For example, if you imagine a grid with many squares, one square would be 1 square unit. Two squares would be 2 square units. If you have a rectangle with 27 squares that would be 27 square units. But it would be really hard and time-consuming to count all 27 of those squares. So you can use a formula. Length * width = area Length of 9 times width of 3 = 27 square units.
Now different shapes/figures have different formulas for area. In a triangle, the formula is (1/2)*base*height, or (base*height)/2. This is because a triangle is half of a rectangle, so you multiply the base and height and divide all that by 2.
