An annuity provides monthly payments for as long as you are alive. If you elect an annuity with survivor benefits, it will provide payments as long as you (or your joint annuitant) are alive.
An annuity is one of your options for withdrawing your beneficiary participant account. If you want a guaranteed stream of payments for as long as you (or your joint annuitant) are alive, an annuity may be the right choice. You can use your entire beneficiary participant account balance to purchase an annuity, or you can use a portion of it to purchase an annuity and choose a different withdrawal option or options to withdraw the rest.