The symbols £ s d are abbreviations derived from the initial letters of the three Latin words for pounds, shillings and pence (£ibra, solidus, denarius). These were the basic denominations of the English currency for over a millennium, until replaced by the present decimal system in 1971. There were 12 pence to the shilling and 20 shillings, or 240 pence, to the pound.
Other denominations are occasionally used in Domesday Book - notably the mark - but overwhelmingly values were given in pounds, shillings and pence. Of these, pounds and shillings were monies of account; only the penny was an actual coin.
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.