I'm a bit rusty on the technology (too many years in management). I'm sure someone will correct me if I've made any errors.

Computers capable of using and creating CIFS file shares (Windows, Linux and, I believe, Macs) create broadcast network ("NETBIOS") packets that contain the computer name. On a conventional office or home network, every computer "sees" every other computer's name broadcasts since it's very common to share resources and there's no real need to hide them from each other.

If the Wifi hotspot has a feature called "wireless isolation" enabled, though, these systems shouldn't be visible to other computers on the network; this feature effectively isolates each computer from any others connected. However, software exists that allows a wifi-enabled computer to capture wireless traffic regardless of the hotspot's isolation setting and therefore glean the names of the computers from their broadcasts. Generally speaking it's only nosy geeks using that software, but it's important to remember that nosy geeks aren't as rare as they used to be. They can easily see any unencrypted traffic to and from your computer. And looking at the encrypted stuff has gotten a lot easier, at least with some encryption methods.

Aren't you glad you asked?