The £ sign stands for the Latin word "libra" meaning
pound, and also means pound in British money.
The "s" stands for the Latin "solidus." A solidus mark or a scilling
(in old English possibly from Norse or old German) mark was a mark or notch
made in a length of metal wire to enable it to be divided into convenient
regular sized pieces. Therefore the English word shilling appears to be
directly related to the word solidus. So the "s" means shilling(s).
The "d" stands for the Latin "denarius," which evolved to the French
"denier". The British penny descended from both, so that the "d" means
penny.
The basic unit of currency was the pound (sterling). The currency now is, of course, the Euro(€).
There were twenty (20) shillings per pound.
The shilling was subdivided into twelve (12) pennies.
There were therefore two hundred and forty (240) pennies per pound.
The penny was further sub-divided into two halfpennies or four farthings
(quarter pennies).
Threepences are self explanatory, being worth three pence. They were
struck in silver until 1944, and in nickel-brass (referred to as brass)
from 1937. The common
name for the old silver threepences was "Joey". The word threepence
would often be pronounced as though there was only a single middle "e",
therefore "thre-pence."
Sixpences again are self explanatory, being worth six pence. They were
also known as tanners.
Florins or two shilling pieces were, just as obviously worth two shillings,
and would also be referred to as "two bob."