Short answers, pulled from the story.
The Spanish Armada was sent to overthrow Elizabeth I, reinstate Catholicism in England, end English support for the Dutch Republic, and stop English and Dutch privateers from attacking Spanish interests in the Americas. Philip II of Spain planned for the fleet to escort an invasion force drawn from the army of Alexander Farnese, Duke of Parma, which was stationed in Flanders.
Alonso de Guzmán, Duke of Medina Sidonia, commanded the armada after the original commander, the Marquis of Santa Cruz, died in February 1588. Medina Sidonia was a competent soldier and administrator but had no naval experience, and he wrote to Philip II expressing grave doubts about the campaign before it sailed.
When the armada left Lisbon it comprised 141 ships, carrying 10,138 sailors and 19,315 soldiers, along with 1,545 non-combatants. The fleet carried 1,500 brass guns and 1,000 iron guns. Storms before reaching the English Channel reduced the number to 137 ships that actually sailed for England.
On the night of the 7th to the 8th of August 1588, the English set alight eight of their own warships and sent them downwind into the tightly anchored Spanish fleet off Calais. The Spanish feared these were explosive "hellburners" and most ships cut their anchor cables and scattered, breaking the armada's defensive crescent formation and causing almost every Spanish anchor to be lost.
Between 44 and 51 ships were lost in total according to historians Neil Hanson, Robert Hutchinson, Colin Martin, and Geoffrey Parker, representing roughly a third of the fleet. Paymaster records show that 25,696 men left Coruña and 13,399 returned, with the lowest estimate of the dead standing at around 9,000. More men and ships were lost to storms off Scotland and Ireland than in direct combat with the English fleet.
La Girona struck Lacada Point in County Antrim, Ireland, on the night of the 26th of October 1588. Of around 1,300 people aboard, only nine survived. The wreck was discovered by a team of Belgian divers off Portballintrae in 1968 and yielded gold and silver coins, jewellery, and armaments now on permanent display at the Ulster Museum in Belfast.