The phrase "in spades" basically means a lot of, or in abundance. It can be used in many different ways, indicating both a positive and negative abundance, and the phrase is thought to come from the game of bridge. A suitable way to use the phrase would be, "I've got problems in spades at the moment. It's not a good time." It is an idiom, and it is believed to have origins in 20th century America.
Idioms are phrases which cannot be understood by their literal meaning or the meaning of their constituent parts. Popular idioms include phrases such as "to kill two birds with one stone," which means to accomplish two goals with one action. Phrases like this are used very often in speech, and can be confusing to anybody who is unfamiliar with the phrase, particularly people for whom English isn't their first language.
In the game of bridge, spades is the highest ranking out of the four possible suits. The suits in a standard Anglican deck of cards are diamonds, hearts, spades, and clubs. In the game of bridge, diamonds and clubs are the lowest scoring suits. The phrase "in spades" was probably spoken many times during games of bridge before it gained its idiomatic meaning.
A common misconception is that the phrase "in spades" is short for "in spadefuls," which would essentially bestow the phrase with the same meaning. A spade is a common tool used for digging, and the phrase "in spadefuls" would conjure up images of piles upon piles of the thing in question. Although spades have been around for longer than the game of bridge, it is generally accepted that this is not the origin of the phrase.
The idiom can be used to refer to anything, whether tangible or not. Someone can be said to have intelligence "in spades" or to have marbles "in spades." Likewise, the phrase can also be applied to negative things, such as problems, allergies, or tumors. The phrase can be used in sentences in place of "a lot of," "many" or other equivalent phrases, but it will often require re-organizing of the sentence structure. For example, somebody could say "I have got a lot of tennis balls," but this would have to be changed to "I have tennis balls in spades" to include the idiom.