In short, Ad Clicks tracks a single specific source (Google Ads), while Visits tracks your website traffic from all sources combined.
Ad Clicks: This metric exclusively counts the total clicks originating from your connected Google Ads campaigns. It does not include traffic from any other source.
Visits: This is a comprehensive metric that counts the total number of unique sessions on your website from all sources. This includes traffic from:
It is normal and expected for your Visits count to be significantly higher than your Ad Clicks count. This is because Visits is the grand total of all your traffic, while Ad Clicks represents just one piece of that total.