The yellow housing colour is a visual key on the line, helping assemblers pick the right connector in a multi-connector panel without reading a label.
IDC termination means no crimp tool, no wire strip — just push the unstripped 26-28 AWG wire into the slot and the contact displaces the insulation. That saves assembly time on a harness build, but the trade-off is that the wire gauge is fixed: 26-28 AWG only. If your cable is 24 AWG or finer than 28 AWG, this connector won't bite reliably. Three positions means three circuits; confirm your BOM line calls for exactly three conductors before committing.