Meaning

noun the basic unit of money in Great Britain and Northern Ireland; equal to 100 pence

noun something for something; that which a party receives (or is promised) in return for something he does or gives or promises

noun a wad of something chewable as tobacco

originLikely derives from the phrase quid pro quo (“this for that”), referring to the exchange of goods/services for money.

Etymology from Wiktionary, CC BY-SA 3.0