Wikipedia
Sol y Sombra is an after dinner alcoholic drink (or digestif), consisting of equal parts brandy and anise dulce (sweet anise or anisette) served in a brandy snifter. This drink is well known in bars and restaurants in Madrid, but not so well known in other cities and towns. The drink's name comes from the Spanish words for sun and shade and refers to different types of seats one can purchase at bullfights. When purchasing bullfighting tickets you can purchase tickets based on sun and shade. The cheap seats are Sol, and are in the full sun, whereas the most expensive seats are Sombra and are fully shaded. A Sol y Sombra ticket has some shade and some sun throughout the day.
As the drink is a combination of the dark brandy (sombra) and the clear anise (sol) we get the name Sol y Sombra.