The shilling was one of the basic denominations of the English currency which lasted for over a millennium until replaced by the present system in 1971. There were 12 pence to the shilling and 20 shillings (or 240 pence) to the pound.
For more detail on the coinage, see R.H.M. [Michael] Dolley, The Norman Conquest and the English coinage (1966); and Sally P.J. Harvey, Domesday: Book of Judgement (2013), chapter 6 and appendix 1..