This measures barometric air pressure. It can predict weather changes, for example a sudden drop in air pressure could mean a storm is coming. When calibrated correctly it can be used to determine altitude, which helps GPS devices to lock on quicker and with greater accuracy.
A gyroscope is a sensor that tracks the orientation of a device, more specifically by measuring the angular rotational velocity. Initially, they were built using a spinning rotor to detect changes in orientation, like twisting or rotation.
Bluetooth is a wireless technology standard that allows data transfers between devices placed in close proximity, using short-wavelength, ultra-high frequency radio waves. Newer versions provide faster data transfers.