These plots describe:
1. the BIAS level in masterbias frames,
2. the read noise (RON) of a single raw frame,
3. the read noise (RON) of a master frame,
4. the collapsed structure of a masterbias in X direction,
5. the collapsed structure in Y direction,
6. the number of bad pixels.
Find more information about GIRAFFE BIAS frames here.
Other QC parameters related to detector properties (like contamination, linearity, gain) are trended here.