Select playback device - help?

Hey folks. I have absolutely zero experience with this stuff, and I can't manage to find any tutorials.

My end goal is replay a single captured packet I saved with wireshark (managed that just fine, saved as .pcap). I'm trying to do this with playcap. I open the file and it prompts me to select a playback device. Is this "playback device" some sort of hardware, or a program?

I apologize if this is a really stupid question, but the only devices listed are Windows and Hamachi for me; I've searched hard and found a few screenshots of other people at this dialog, and it shows various capture devices and such, and I'm just really not sure what I need to replay this packet.