Apart from the common units of length, you are used to, feet, which is the plural form of foot is also used in measuring the length of anything, although it is a non-SI unit of length, it is included the imperial and the United States customary systems of measurement. On the other hand, square feet are a unit for two-dimensional measurements, such as area.
As you know that the area of anything is calculated by multiplying the length and width, the unit square feet" is also a product because the unit of length and width i.e., feet, will also be affected to give square feet. For example, 12 feet multiply by 3 feet is equal to 36 square feet. Anytime you see the symbol 'ft,' it simply represents feet, whereas square feet are "ft²" or "sq ft" as its symbol. If 1 foot is equal to 0.3048 meters, 1 square foot will give to 0.092903 square meters.