Horizontal signs, also called road markings, are those traffic signs that are painted on the road or asphalt and offer the driver information to circulate safely. Headlight collectors are often used as a complement to horizontal road markings to retro-reflect the light they receive incidently.
Of course, horizontal ones must be respected with the same rigour as vertical ones. Zebra crossings are an example of horizontal signs, whose purpose is to indicate the presence of a pedestrian crossing, although there are many others, such as:
Solid line: unable to cross lane
Dashed line: means that you can overtake or change tracks, either on a one-way street or another in both directions.
Yellow grid: prohibits blocking the intersection
Yellow Zig Zag: no parking
Straight arrow together with arrow to the side: lane selection, forces to keep the selected lane.