So I'm reading Genki II where they introduce なら. There's a dialogue which has the following context: a guy asks his female friend Kyouko to cover for him at work (he's an English teacher). The friend is hesitant and says:
- 私、英語を教えたことがないし、できない。 to which the guy answers:
What is the literal meaning of this? "You're better at English than I am, so if it's you, you can"? This makes literally zero sense. So I suspect it actually has the meaning of "If there's someone who can do it, it's you" but even if my assumption is correct, I still can't see how なら logically fits into this.
Then there's also another dialogue example. Context: a guy and a girl are in a fitness store. They see a fitness machine and are discussing it:
I've read all I could find on the Internet about なら and while some examples make sense, I still don't understand it in actual, unadapted real-life sentences, even as simple as these ones. What does it mean in the above dialogue? "If it's this machine, you can use it at home"? Surely that's not correct.
Thanks in advance.