What do W (watts) and lm (lumens) mean?

W = watts (electric power consumption)
Watt is a unit that expresses electric power. For example, a 60 W bulb uses more electricity than a 6.3 W bulb. The wattage is not a unit of brightness; it shows how much electric power is consumed. You need to check the number of lumens (lm) or candela (cd) to know how much light a bulb will give off.

Lm = lumens (brightness, total luminous flux)
Lumen (lm) is a unit that expresses the brightness of the light that a source (bulb) emits in all directions. The higher the lumen rating, the brighter the bulb.

Cd = candela
Candela (cd) is a unit that expresses the brightness of the light that a source (like a reflector bulb) emits in a specific direction. The brighter the light, the higher the candela rating.

K = Kelvin
Kelvin (K)  is a unit that expresses colour temperature. In other words, it shows how red (warm) or blue (cool) the colour of light is. Higher Kelvin ratings indicate more blueish light.

IP = Ingress Protection
Bathroom and outdoor lighting requires protection against damage from water and solid particulates. IP ratings express the level of protection with a two-digit number. The higher the number, the more protected the product is.