Meta Business Help Centre
About location targeting

Reach people based on locations such as country, county/region or town/city.
The location targeting selection that you choose will be used to find people living in or recently in the selected location. This helps you reach many people within a specific area during a certain time frame.
Note: Most advertising objectives allow you to refine your audience this way, though the Awareness objective uses shop location features to connect people with nearby physical businesses.
Meta technologies use a variety of signals to show ads to the people who are a part of your location targeting selections. As these signals vary, complete accuracy cannot be guaranteed. You may occasionally see a small number of ad impressions, or even receive a message or lead, from outside of your location settings.
Sometimes people may also see an ad organically. In these instances, you may have engagement, such as likes, comments and shares on the ad outside the targeted location. We may also show preview ads to people connected to the business, even if they're outside the targeted location. You'll not be charged for preview impressions.
How to measure location targeting
Your campaign reporting can give a clear representation of location targeting results. If you use third-party tools such as Google Analytics to compare results, bear in mind that their reporting may not match ours because they use different location targeting methods.