Wikipedia
A 'Veinticuatro' (meaning Twenty-four) or 'Caballero Veintiquatro' (Knight/Gentleman Veintiquatro) was an official in several Andalusian cities in pre-modern Spain, notably Úbeda, Baeza, Jaén, Córdoba, Seville, Jerez de la Frontera and Granada. The office or post itself was referred to as a veintiquatría. It was largely equivalent to the role of an Alderman, or Councilor, in English local government. It was an office reserved exclusively to those of noble birth- ( Hidalgos, of which there were many in Spain), though, like many official positions, the post could be bought and sold among Hidalgos. Many of the Conquistadors, and the merchants who established the Spanish Empire in America, (for example, the immensely rich Diego Caballero, were Caballeros Veintiquatro, or bought the post to display the new position in Spanish society the wealth gained in the Americas had allowed them to achieve.
The Veintiquatro name apparently derived from the original number (24) of members of a town council, but this varied with time and from town to town. They had immense privileges their duties were many and various, from deciding and collecting local taxes, to regulating and inspecting markets and shipping and including the relief of poverty and inspecting prisons.