Crédit Lyonnais is a really long name for a bank that was started over 150 years ago in France. A bank is a place where people go to put their money in a safe place, and sometimes they borrow money from the bank too.
Crédit Lyonnais is famous because it helped a lot of big companies and famous people in France get their start by lending them money. It's like when you ask your mommy or daddy for some money to buy candy at the store, but instead of just buying candy, you use the money to start your own candy store and sell your candy to other kids too.
Sometimes, the bank makes mistakes with the money it has, just like we sometimes make mistakes when we are playing. Crédit Lyonnais made a really big mistake with some money they loaned to a company that was not doing very well. This mistake cost the bank a lot of money and made it famous all around the world for a long time.
After that mistake, the bank had to work very hard to earn back people's trust and to make sure it was being a responsible bank. Today, Crédit Lyonnais is still a well-known bank in France and around the world, and many people still trust it with their money.