What does the 'fried egg' traffic sign mean and why should all drivers know it?

The traffic sign colloquially known as the 'fried egg' is a diamond-shaped road marker featuring yellow and white colors. Officially identified by the Spanish Dirección General de Tráfico (DGT) as code R-3, the sign is a notable component of the national driving curriculum.

Despite its prevalence, the sign is frequently misunderstood by motorists. It is recognized as one of the specific traffic indicators that most commonly leads to incorrect answers during the theoretical portion of the Spanish driving examination.