A Roth option as part of my 457b?

I have a 403b and 457 through my employer. I have been maxing the 403b just because I needed to pick one to start contributing to.

My understanding of the flowchart was that I should have opened a roth IRA first, so I called fidelity (who has my work accounts) to open a roth IRA. The nice lady told me that I have a roth option in the 457 I think.

I... Don't understand how that works. I opened the IRA anyway because that is what I had planned to do and she said it wasn't stupid. I put 1,000 in it but haven't invested it yet, also because I don't understand their prompts after I say I want a target date fund.

Now that it is open, should I still try to max it in 2024 or should I be contributing to just the 403b and 457b and having some of those contributions be roth? I don't even think I understand what that means. If it matters I made about 110,000 last year and will likely make about 130,000 this year.