What does the joke on the phone mean?

Deposits have current and fixed periods, and "death period" is a popular term for fixed periods.

You can save money and withdraw money at any time, and the interest rate is relatively low.

Time deposits, such as one-,three-or five-year time deposits, have much higher interest rates than current deposits. If you have a lot of money and don't need it urgently, of course you choose to save your life.

You need to take it out when the deposit period ends.