What are the details (screenshot?) showing in Network? If it has a green dot, please also show the "Advanced" sheet. You can blur/block out any personally identifying info, of course.
My Pref shows how many "friends and neighbors" have WiFi. All but one are using passwords to prevent others from using their bandwidth.
There is also a "xfinitywifi" entry in that list. That is just the new, un-alphabetized name for Comcast (still a monopoly here, of course). They claim that it is for use by any guests who would want to connect to the web and that none of the bandwidth will count against my limits. I trust them about as far as... well, leaving politics out of this, I'll simply say I have disabled that.