The league is a ancient unit of length that doesn't below to a unit system. Its symbol is simply - league.
It was originally an ancient Celtic unit as well as being common in Latin America and meant the distance "a person could walk in an hour". It is no longer a recognised unit in any nation.
Once it started to be quantified, in Argentina (legua) it represented 5.572 km, in England it was quantified as 3 miles and at sea a league is 3 nautical miles (3.452 miles).
The pica is a unit of length in the field of typography and uses the symbol pc.
There are 12 points in 1 pica. 1 pica represents approximately 1/6 of an inch.
Picas are expressed using numbers and a lower case p on software such as Adobe InDesign - for example 8p6 which would represent 8 picas and 6 points (or 8.5 picas).
The Pica is very useful in measuring and calculating the space needed to print letters and words on paper - for example when laying out books or magazine articles; the font lengths are quanitified by the number of characters per pica (cpp).