Canon EOS RP Instruction Manual page 307

Shutter Speed Display
For example, "0"5" indicates 0.5 sec. and "15"", 15 sec.
o
If the lowest f/number blinks, it indicates underexposure.
o
Turn the < 6 > dial to set a slower shutter speed until
the aperture stops blinking or set a higher ISO speed.
If the highest f/number blinks, it indicates overexposure.
o
Turn the < 6 > dial to set a faster shutter speed until
the aperture stops blinking or set a lower ISO speed.
Shutter-Priority AE
99