What is "Television" in System Information report for an external monitor (that is not actually a TV)?
1.What does Television:Yes mean?
It means your macbook is sending the color to your display not in RGB but in YCbCr space instead of RGB,which could lead to poor picture quality.

2.Solution:
Override an EDID (Extended_Display_Identification_Data) setting to force the RGB colour space

Threads  about forcing RGB mode instead of YCbCr

You can force RGB mode by following Turtorial on how to force RGB mode

This is long standing bug that Apple refuses to fix and that is not simple to work around.