This is a photo of an RER A (red line) stations panel.
These panels can be found along each RER train platform for each direction of travel. This panel in particular is in the direction Cergy-Le Haut (A3), Poissy (A5), Saint Germain-en-Laye (A1).
Each name listed on the panel represents a station stop. The next train that arrives will stop at all station names that are lit with a yellow square.
This train in particular will be traveling along the A1 branch of RER A, ending at Saint-Germain-en-Laye.
