If I recall correctly pH stands for "potential Hydrogen" and is a scale to monitor the relative presentce or absence of chemical Hydrates. Like what was said before, pH level measures the degree of alkalinity, or acidty of certain materials. It is very important to maintain a proper pH in a growing situation!
K levels refer to lighting. Also called the "Kelvin color temperature", it is a scale that represents the primary color spectra of a light source according to a particular "K" number. Many moons ago, Lord Kelvin did experiments with solid blocks of Carbon. He found that when he heated them up to various temperatures - they would "glow" in unique colors. Different temperatures for all colors in the spectrum. Today we use these K numbers to indicate what spectrum of light a certain bulb will give off. I.E. 6,500 K for vegging, or 2,700 K for flowering.