What is "domain specific and precise language"

Domain-specific and precise language make writing more authoritative. If you use words that are less vague it makes it seem like you can get the sentences to make more sense with less detail.

how is this? I didn't know what you wanted

Domain specific and precise language in informative / explanatory writing gives you (the author) creditability. It makes you look like you know what you're talking about. It is more specific and making your writhing clearer and easier to understand because you aren't being generic.