Know-how, in the most rudimentary sense of the term, means that one has the necessary knowledge or skill(s) to accomplish what needs to be done at that time.
For instance, a plumber has the know-how to unclog a stopped-up drain pipe. A chef has the know-how to prepare food without botching the attempt. But then, something as simple as cooking eggs without making them stick to the pan can be achieved by almost anyone with proper tools and/or resources (I use a Teflon pan with butter).
A tech-savvy teen has the know-how to navigate a new touch-screen phone that some more old-fashioned people pull their hair out trying to figure out how to work.
So, all in all, know-how is largely acquired. But sometimes it just has to do with common sense and a lot to do with the environment one came up in.