What is Negative keywords?
Negative keywords stop your Google Search ads from showing for searches you don't want, such as ‘free’, ‘DIY’ or ‘jobs’, so you stop paying for clicks that never buy.
The search terms report shows the real searches that triggered your ads. Terms with spend and no orders are candidates for negatives.
Review negatives carefully: an over-broad negative can block searches that do convert.
Example
Adding ‘free’ and ‘wholesale’ as negatives for a face-wash brand that sells only at retail prices.