This is a corning optic/optical cable, 13ft long with same end on both end. likely uses are for home computer, modem, other devices networking for AT&T, Verizon, etc.
The marking on the cable (there is a pic but may not be easily readable) is:
Corning Optical Cable 01 06/20 ss-946Ic1 - 001 SMF - MBR E2191 04 (UL) OFNR C9UL) OFN-FT4 1433 MT