Humans give off mostly infrared radiation, which is electromagnetic radiation with a frequency lower than visible light.
This effect is not unique to humans.
All objects with a non-zero temperature give off thermal radiation.
How much energy do humans emit?
The average human, at rest, produces around 100 watts of power.  Over periods of a few minutes, humans can comfortably sustain 300-400 watts; and in the case of very short bursts of energy, such as sprinting, some humans can output over 2,000 watts.
Do humans radiate light?
The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal. Past research has shown that the body emits visible light, 1,000 times less intense than the levels to which our naked eyes are sensitive.
Can humans become bioluminescent?
One is that in human being such reaction of bioluminescence do not occur. In bioluminescent animals the enzyme luciferase catalyses the reaction of luciferin and oxygen to form oxyluciferin. Thus this luciferin luciferase reaction occurs in organisms like dinoflagellates, fireflies etc. Hence, humans cannot Glow.