What is a bob in money?

Excuse me, could you please clarify what you mean by "a bob" in the context of money? Is this a colloquial term for a specific currency unit or denomination? If so, could you provide some context or an example of where this term might be used? Alternatively, is "a bob" referring to a specific financial instrument, investment, or other financial concept? I'm eager to understand your question and provide a helpful answer.