Let’s look at an example. At Yoast, we call our courses platform the “Yoast Academy.” So at first, it might seem logical for us to optimize for the keyword “Yoast Academy.” However, when we analyze traffic data, it turns out that our audience searches for “Yoast courses” way more often. So it makes much more sense to optimize for that term instead. Every company has its internal vocabulary, which often doesn’t match the vocabulary of its audience. Therefore, you should always select your keywords from your audience’s perspective. You can use Google Trends to research how often certain search terms are used compared to other terms.
The SEO starter guide describes much of what your SEO will do for you. Although you don't need to know this guide well yourself if you're hiring a professional to do the work for you, it is useful to be familiar with these techniques, so that you can be aware if an SEO wants to use a technique that is not recommended or, worse, strongly discouraged.