Could very well be audio in for connecting to video. You'll need to locate the audio out of your TV first.
Well my dad has a an old Panasonic SA-Ak57 and when looking throught the manual it show it being hooked up to a tv. it has a AUX 1 and 2 port, Audio L and R for both. Any ideas how to hook it up? Do i just attach red white from tv to red white on the back of the system? BTW if it helps here is the manual.