The phrase "gave once over" is a colloquial way of saying that someone gave something a quick but thorough inspection. There are a few synonyms for this phrase that can be used interchangeably depending on the context. Some alternatives include "scanned," "inspected," "examined," "surveyed," and "checked out." Each of these phrases implies a similar idea that someone is taking a cursory look at something in order to gain a basic understanding of it. Regardless of which phrase is used, it is clear that the speaker is not going into great depth or detail about the thing being inspected.