# why did you not put my money ... interest?

The nobleman uses a question to rebuke the wicked servant. Alternate translation: "you should have put my money ... interest." 

# put my money in the bank

"lent my money to a bank." Cultures that do not have banks might translate it as "let someone borrow my money."

# bank

A bank is a business that safely holds money for people. A bank lends that money to others for a profit. It also pays an extra amount, called interest, to the people who keep their money in the bank.

# I would have collected it with interest

"I could have collected that amount plus the interest it would have earned" or "I would have gained a profit from it"