Anchor text is the clickable words in a link. Google uses it to understand what the linked page is about. Get it wrong and you confuse Google.
What Not to Do
"Click here." "Read more." "This article." These tell Google nothing about what you are linking to. Waste of a ranking signal.
What Works
Descriptive, natural anchor text that tells readers and Google what to expect. "How to write SEO blog posts" is way better than "click here." Include keywords naturally — never force them.