Wikipedia defines this as “a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation" It is a widely held but irrational belief in supernatural influences, especially as leading to good or bad luck, or a practice based on such a belief. Here are some common superstitions you are likely to hear in English.
Knock on wood
We say this after we have talked about having been fortunate in some way and immediately worry that by having expressed that thought, we may have jinxed it and thus receive bad luck. We either say “knock on wood” or actually do it. The British say “touch wood”.
Cross your fingers
This is a gesture in which you actually put the index finger over the middle finger or vice versa. We do this when we hope for a lucky or good outcome to something. This is a very old gesture dating back to early Christian times. It is said that at that time two people would cross their index fingers when making a wish.
Opening an umbrella indoors
This is thought to bring bad luck. It’s not clear how the superstition arose, but it has been around for a long time. I remember that as a child I was strongly scolded not to do it.
Breaking a mirror
Breaking a mirror is said to bring 7 years bad luck. This superstition appears to come from the belief that mirrors not only reflect your image, but also hold bits of your soul. In the old days in the American South, people covered the mirrors in their house when someone died because they were afraid their soul would be trapped inside.
In east Asian countries, there’s a superstition that if you sneeze, someone is talking about you. Moreover, the number of times you sneeze is a sign as to what they’re talking about. For example, one sneeze means something good has been said, two means something bad has been said, three is a sign that someone is in love with them, and four is a sign that tragedy will befall their family. When I was growing up my grandmother said that it meant you would “kiss a fool”. Even to this day when I sneeze I often think or say, “I guess I am going to kiss a fool.”
 https://en.wikipedia.org/wiki/Superstition  https://www.ceenta.com/news-blog/6-myths-superstitions-and-more-about-sneezing#:~:text=For%20example%2C%20one%20sneeze%20means,tragedy%20will%20befall%20their%20family.