Canon EOS 7D Mark II Instruction Manual page 219

If the lower f/number blinks, it indicates
underexposure.
Turn the <6> dial to set a slower shutter speed
until the aperture stops blinking or set a higher
ISO speed.
If the higher f/number blinks, it indicates
overexposure.
Turn the <6> dial to set a faster shutter speed
until the aperture stops blinking or set a lower ISO
speed.
Shutter Speed Display
The shutter speeds from "8000" to "4" indicate the denominator of the
fractional shutter speed. For example, "125" indicates 1/125 sec., "0"5"
indicates 0.5 sec. and "15"" is 15 sec.
s: Shutter-Priority AE
219