Better late than never. They shorthand, and usually from the latin:
po = per os (by mouth)
pr = per rectun
pv = per vaginum
for injections:
im = intramuscular
iv = intravenous
i, ii, ii = roman numerals for the number of tablets 1, 2 ot 3. Also you see T,TT,TTT.
bd / bid = bis in die (twice a day)
tds / tid = ter die sumendum (three times a day)
qds / qid = quater die sumendum (four times a day)
prn = pro re nata (as required)
stat = statim (immediately - heard very often in episodes of E.R.)
Mane / nocte (morning/night)
I am unsure of the T with a mark on, I have a friend who will know, it is probably just:
'
T = 1 tablet
"
T = 2 tablets