Civil time in lay man's terms is solar time plus 12 hours. For example, if you want to know Civil time, you add 12 hours to solar time. And solar day begins at noon while civil day begins at midnight. So adding 12 hours makes sense. Civil time is not normally used because it depends on an observer's longitude and this might change, Instead we use standard time which remains pretty much the same throughout a given time zone

Hello Sideeq,

Civil time is the local time based on the universe. Civil time is formally defined as mean solar time plus 12 hrs , the civil day begins at midnight , while the mean solar day begins at noon. Civil time is occasionally adjusted by one-second increments to ensure that the difference between a uniform timescale defined by the atomic clocks
does not differ from the earth's rotational time by more than 0.9 seconds.

I hope your question has been answered properly.

All the best!