Bit depth is how many bits encode each individual sample, and it sets the dynamic range — the distance between the noise floor and the loudest undistorted level. Each bit adds roughly 6 dB, so 16-bit gives about 96 dB (the CD standard) and 24-bit about 144 dB, more than any room or microphone needs. 32-bit float is different: it stores values as floating point, so levels can briefly exceed 0 dBFS without clipping and be pulled back later, which is why field recorders and DAWs use it. The practical rule for video work is capture at 24-bit, mix in 32-bit float, deliver at 16- or 24-bit.
