Silent Bob is a character from the Kevin Smith universe, and is in fact played by Kevin Smith. He spends most of his time with Jay hanging out in front of a store selling drugs.  As his name suggests, he almost never speaks, but when he does, it is usually very helpful advice. He is shown to clearly be much smarter than Jay (Which admittedly isn't saying much), and also much more patient and good-natured. He puts up with Jay's stupidity and verbal abuse most of the time, but loses his temper at least once.