Hello!
The biblical meaning of "pitch" is asphalt or bitumen in its soft state, called "slime", found in pits near the Dead Sea. It was used for various purposes, as the coating of the outside of vessels and in building and construction.
"He that toucheth pitch shall be defiled." This comes from the Apocrypha and is a warning against mixing with the rich. 'As the wild ass is the lion's prey in the wilderness, the rich eat up the poor. ' In general, it is a warning against wickedness.
I hope that helps!