Google can show your search campaigns across two different areas.
1) Google Search: These are Google Search owned properties such as Google.com, Google.fr, and so forth for various countries and properties.
2) Search Partners: These are sites that are not Google primary search and include a combination of Google owned and non-Google owned sites. With search partners your ads can show on sites from YouTube to Google Local to other search sites, directories, or pages related to a user's search.
Some companies preform poorly on search partners as these can be non-search sites where ads are triggered based upon other information, such as products displayed by a directory site. Some companies do just fine with search partners. What is important is to understand how you are preforming on Google Search vs Search Partners so you know when to take action.
If your Search Partner data is significantly worse than your Google Search data, you will see an alert on your dashboard:
Just click the alert and you'll be taken to the campaign screen. You'll see a gear icon with a red alert if the settings need to be examined.
Click on the gear icon and open the campaign settings and performance data. Go to Networks, and examine how your Google Search vs Search Partner data is performing for that campaign. If you want to disable the search partners, just click the 'disable search partner network' button, and this will disable Search Partners from showing ads from that campaign.