The lumens (lm) definition is: “a unit of luminous flux in the International System of Units, that is equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions.”

In other words, it’s the measure of how much light you are getting from your lamp. 1 Lumen = 1 Candle, the more lumens you have the brighter the lamp will be, unlike wattages which has no direct relation to brightness.