FM dial actually.
87.7 FM is actually the audio signal from analog TV channel 6. The FCC still allows low-power analog TV stations to operate on channel 6.
“MeTV FM” is actually a TV station, WRME-LP, that broadcasts from the top of the building formerly known as the John Hancock Center. The FCC requires them to broadcast a picture of some kind, so if you tune your TV (if it has OTA reception) to channel 6 (not 6.1), you might be able to see their pictures and hear their audio.