Three ounces is equal to 85 grams or about 0.2 pounds. This is a dry measurement, also called a "weight measurement." Three fluid ounces is equal to 90 milliliters or 6 tablespoons. This is a liquid measurement, also called a "volume measurement."
Fluid ounces can also be converted to cups. One cup is equal to 8 fluid ounces (half a pint), so 3 ounces is 3/8 of a cup. Also, for dry measurements, 3 ounces can equal different weights, depending on the ingredient being measured. For example, 3 ounces of flour or powdered sugar would weigh a little less than 3 ounces of a denser sugar, like brown sugar.