What is a left bank in catalyst system 98 Chevy pickup?

The term "left bank" is not typically used in the context of vehicles, let alone in the specific case of a 1998 Chevy pickup. Instead, "bank" usually refers to a group of cylinders in an engine. For instance, an "engine with dual overhead camshafts has separate cylinder heads in either the left or right bank of the engine, usually with two cams serving 4 valve heads." Would you like to know more about the engine of a 1998 Chevy pickup, or can I clarify the query in any other way?