Hi there, you might be interested in some old answers by u/kieslowskifan below which go into more detail about the history and economics of hyperinflation.
The short answer is that over a very short period of time the Mark hugely decreased in value. This led to things like people being paid in wheelbarrows full of cash and loaves of bread costing one billion marks. This was caused by excessive government spending during the First World War and aggravated by Germany's poor economic situation after losing. It was eventually solved when the Weimar government issued a new currency at a much lower denomination. (Das kann ich auch auf Deutsch erklaeren wenn Sie nicht verstanden haben)