When reviewing the Search terms report for your Shopping campaigns, you notice several terms that aren’t relevant to what you’re advertising. How can you use this information?
Add the terms as negative keywords
Adjust your product data feed to include irrelevant terms
Increase your Quality Score by including irrelevant terms in ad content
Increase your bids for more relevant keywords
Negative keywords are an important part of every campaign because they help make sure that your ads appear only to people looking for what you offer. This added level of control can help you increase your clickthrough rate (CTR), reduce your average cost-per-click (CPC), and increase your ROI.
Read more here: https://support.google.com/adwords/answer/105671