Why it rotates around its axis in 23 hours 56 minutes 41 seconds?

Answer 1

If you mean, as opposed to the observed 24 hours of day, Earth's real rotation is every 23 hours 56 minutes, approximately; but since during its rotation it moves around the Sun, Earth has to move around a bit more than one full rotation to catch up with the changed position of the Sun, i.e., until the Sun is overhead again in a certain place.