By default, the Spotlight feature will index everything in your Mac and return the results when you do a search. Here is how you can prevent Spotlight from indexing a particular folder.
1. Go to “System Preferences -> Spotlight”.
2. Click the “Privacy” tab.
3. Click the “+” button to add the folder that you don’t want Spotlight to index. (You can drag a folder or disk to add it to the list as well)
That’s it.