The penny was one of the basic denominations of the English currency. It 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.
Pounds and shillings were monies of account; only the penny was a coin. The penny was, in fact, the only coin in use at this time, the halfpenny or farthing being pennies cut in a half or into four pieces.
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..