I agree, you pretty much can’t break Excel*, and there’s loads of online help with examples.Honestly, there's so much free information online about Excel functions that I wouldn't personally spend money on a book (although for some people that's the best way to retain information, I'm not one of them!).
Everything I've learned has been through searching for a feature I didn't know how to achieve.
The function search is pretty useful too, with some help built in.
* But be careful of circular references, anything self referential can cause a crash, though generally not in “small” workbooks.