Roaming nowadays has largely been surplanted by E-sims, but in this scene they're talking about inter-state roaming charges. The woman in the screenshot is from florida and she's supposedly getting roaming charges while in Pennsylvania
Even when the show came out roaming wasn’t a thing. Roaming has nothing to do with esims and it has to do with which cell network you are connected to. In the American context, if your provider is Verizon but where you are you can only connect to T-Mobile towers then you are roaming.