I have been seeing this phrase on the BST section but I didn't understand it. Anyone here who can tell the meaning?
I think what they mean is that a link is placed not as a "stand alone", ad-type, but rather as a part of (ideally topical) text, i.e. within an article body, e.g. Those kind of links have much less chances to be treated by search engines as paid links, as compared to stand-alone links.