Flight From Money is a situation where people in an economy lose faith in paper money and resort to barter or saving in the form of assets like gold or silver.
Flight from money can occur during periods of hyperinflation. Hyperinflation is a situation where the inflation rate becames very high. This means the value of money is rapidly deteriorating. Under situations of hyperinflation, normal economic transactions can break down as prices change so quickly.
Also, if an economy experiences hyperinflation, people may switch to using another currency which is considered safe and likely to retain its value.
For example, during the Zimbabwe hyperinflation of 2008-09, people switched to using the US dollar.