A bench is a long seat that is designed for more than one person to sit on at once. Benches sometimes don't have a backrest. Benches are often seen in parks, or by bus stops.
French is the language spoken in France, people from France or anything related to France.
A trench is a long, narrow hole. Trenches are often dug to lay electrical cabling or water pipes. 'Trench' can also be used as a verb, as in "we need to trench from the street to the house".
A wench is an old word used to describe a poor, young woman who must work during a time where many women didn't have jobs. Wenches would often work in bars serving drinks.