That is a vintage wall-mounted cigarette rest/ashtray (Wandascher).

• Where & Why It Was Used: These heavy metal fixtures were extremely common in European public venues, train cars, and bar restrooms during the mid-to-late 20th century, back when indoor smoking was ubiquitous.
• How It Works: Placed next to urinals or stalls, the grooved teeth gave patrons a designated, heat-safe spot to rest a burning cigarette (or cigar) horizontally while using the facilities or washing up, preventing burn marks on porcelain fixtures or littering on the floor.
• Tipping Mechanism: The top tray is hinged—when tipped or lifted, the ash drops down into a lower catchment box or trough (though the bottom catch pan on this particular vintage unit appears to be missing or integrated behind the tile).

While smoking in indoor public spaces in Germany has long been banned, many vintage Berlin kneipen and dive bars leave these fixtures installed as a piece of nostalgia.