In India there are certain observations with Astrology. Like you may notice very filmy side with which western people view the astrology. But in India everything is viewed with Karma in context of astrology. Be it relationship, marriage, life and death and what is pending all of this is viewed with karma.
And one of the karmic planet in Indian astrology is the Saturn. And this planet shows people how the karma is meant to be repaid and how the life is meant to be managed. Karma means doing things that would free you from the debt. And saturn is meant to be the guy that would guide you on how that would work.
Saturn is not an easy planet as per the Indian astrology. The way hinduism views saturn he come every 30 years for 7.5 years breakdown and makes you pay the karma. And he is offering you chance to pay off for your bad deeds. And often people use the horseshoe ring in right hand middle finger to respect saturn and stay submissive to his effects.
Horse shoe is one of the items through which even the ghosts can be repelled. Like some forms of demons which Saturn happens to eradicate happen to be afraid of the horseshoe. And so often peopole use it at the top of the door and hang it there. I never used to believe in these things but with pandemic I had some of the experience which made me believe.