retirement

You need to talk to your HR. I think most employers require that you work a minimum number of hours a week to be eligible to contribute to a 401k and for them to match it.

Every employer is different both to the number of hours worked and the different types of prorams they offer. You need to take advantage of anything your employer offers. If they don't offer anything then do it yourself in your own IRA program. Its good that you are asking about retirement as too many nurses don't, particularly the younger ones. But when you are young that is the most effective time to start a retirement program. My bias is to a Roth IRA unless you can get a pre-tax and or match program from your employer.

Whatever you do don't do nothing. if you do nothing then you will squander your most valuable resource... time. Time until you retire is the most important part of any retirement program.

Most places don't offer "retirement" (I presume you mean a pension?) anymore, it's up to you to pay for and plan for your own retirement. Good luck!