Not the person you replied to, but I've thought about this question myself and I think I've come up with a half decent analogy to explain it. (Someone more qualified can help me iron out any flaws).
Let's say there's an app to order pizza specifically from Dominoes. A generalisation of that idea would be an app to order a pizza from not just Dominoes, but from any food chain that offers pizzas.
An abstraction over that idea would be an app that offers some arbitrary thing in exchange for something that acts as a currency/payment(notice how we've entirely omitted money as a hard requirement).
So in essence, we went from:
An app that maps your money to a Dominoes pizza
Money -> Dominoes pizza at home
to an app that maps your money to any pizza from a food chain(generalisation)
Money -> (Pizza Hut, Dominoes, Papa Johns, ...) pizza at home
to an abstraction over the entire thing
Something to act as a "payment" -> Some return for said payment
An example I can think of for the last would be some service where people can exchange their skillset as a payment with each other. For example, if you know how to cook, you could cook something for a person, and in exchange they could offer a service using their skills to you(mabye help you clean a part of your house). So them cleaning a part of your house acts as a general payment, and you offering to cook for them is a service, it's sort of a abstract barter system over money.
edit: became french for a split second and spelt home as homme
Let's say there's an app to order pizza specifically from Dominoes. A generalisation of that idea would be an app to order a pizza from not just Dominoes, but from any food chain that offers pizzas.
An abstraction over that idea would be an app that offers some arbitrary thing in exchange for something that acts as a currency/payment(notice how we've entirely omitted money as a hard requirement).
So in essence, we went from:
An app that maps your money to a Dominoes pizza
Money -> Dominoes pizza at home
to an app that maps your money to any pizza from a food chain(generalisation)
Money -> (Pizza Hut, Dominoes, Papa Johns, ...) pizza at home
to an abstraction over the entire thing
Something to act as a "payment" -> Some return for said payment
An example I can think of for the last would be some service where people can exchange their skillset as a payment with each other. For example, if you know how to cook, you could cook something for a person, and in exchange they could offer a service using their skills to you(mabye help you clean a part of your house). So them cleaning a part of your house acts as a general payment, and you offering to cook for them is a service, it's sort of a abstract barter system over money.
edit: became french for a split second and spelt home as homme