Of course, details are in Spanish so unless you have a grasp of the language, tickets can be a bit confusing.
Abono 3 Días – this indicates you have a 3-day ticket
Tribuna and Zona – Tribuna is your grandstand – some grandstands are also split into numbered zones.
Fila – this is your row number.
Asiento or Butaca – this is your seat number.
Alta or Baja – if you are seated in the Main Grandstand, this is split into the upper section (Alta) and the Lower section (Baja). Make sure you head to the correct section, as the zones, rows and seat numbers are replicated in the upper and lower sections.