The Shemitah is one of several recurring prophecies in the bible that have both a blessing and a cursing attached to them. If the sabbath year (ie one year every seven) is observed as a year of rest, God will bless and prosper the nation and the family that observes it. But if it is not observed, God will curse that nation or family with economic failure and/or hardship. History repeatedly proves out this prophecy as being true as every seven years right on schedule on the last day of the 7th year there is either an economic blessing, or more often, a collapse or sharp correction in the economy.
So the Shemitah is a time of divinely powered economic reset. Also, after every 7 Shemitah's at the end of the 49th year, is what has been referred to as a "Super Shemitah" (the term was coined by Jonathan Cahn) which is the most powerful of all the Shemitah's and sees the greatest blessing or market correction/crash out of all the prior six Shemitah's. This is then compounded by the Jubilee year which immediately follows it the next year. So at the end of the 49 years you get a double whammy of a Super Shemitah on the last day of the 49 years, and the 1st day of the Jubilee year the following day.
(*Do you have a better description, or did you find an error? Please let me know.