As stated above, clipless pedals use special cleats and shoes to hold your foot in place on the pedal. “Float” refers to how much your foot can move while clipped into the pedal. This is important when it comes to rough terrain and areas where precise footwork is necessary. Float is typically an angle from 0 to 15 degrees, and the exact amount of float will depend on the specific cleat.
Clipless pedals involve specific ways of detaching them, the most common being to pivot on the ball of your foot so you can twist your heel outwards. “Tension” refers to the amount of resistance needed to do this. The angle of release is also important, as it determines on what plane your foot with disengage from the pedal. These are both crucial in regards to how quickly you can unclip your foot from the pedal, so take these factors into consideration as well.