Leviticus 25:9-10 "Then you shall cause the shofar to sound...and proclaim liberty throughout all the land"

HaShem created all men as free individuals.

Different situations arise and a person may end up being sold as a slave (See Positive Mitzvah 232).

He may have been serving his master for many years, but in the Yovel year he must be set free.

We are commanded to sound the Shofar on Yom Kippur of the Yovel year and proclaim all slaves free.

The blowing of the Shofar arouses and inspires everyone to remember that HaShem is Master of the Universe and He declared that all slaves must be freed.