what does 2700k mean?

im new to this shit so dont bitch, just answer if u can. i see 2700k and 6400k at the end on names of light bulbs. what does it mean?

The K stands for kelvin, thats how hot the light burns and is measured in wavelengths.

Use the 2400 for flowering and the 6500 for vegging

Different color spectrums/temperatures

"The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units (SI) and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics. The reference point that defines the Kelvin scale is the triple point of water at 273.16 K (0.01 °C; 32.02 °F). The kelvin is defined as 1/273.16 of the difference between these two reference points." -wiki

thanks guys