Power: This is the instantaneous power output typically measured in watts which is calculated by multiplying torque by cadence. Power data is transmitted to the head unit and 2 Hz (twice per second) with the maximum frequency of power display typically being every second.
Most ANT+™ enabled head units also have various power averaging and maximum power display options that are all based off this power number. Please refer to your head unit user manual for details.
Cadence: Cadence is measured by built-in accelerometers
Torque effectiveness: Indicates what percentage of your total pedal stroke power is being used to move the bike forward. The remaining percentage (100%-TEff) is the amount of pedal stroke power you are essentially wasting either by not completely lifting your leg on the upstroke or applying power in a useless direction (backwards). Values of 60-100% are typical. A value of 100% indicates that all of the power delivered on the pedal stroke was in the forward direction.
Pedal smoothness: Indicates how evenly power is being applied over one rotation of the crank. Values of 10-40% are typical. A lower value would indicate power is being applied quickly in only one part of the pedal stroke. A higher value indicates the power is being applied more evenly over a bigger range of the pedal stroke.