To ensure that your content is catered towards the correct audience, there are two methods to do so, depending on how your webshop is set up. Users can be targeted based on language or region. 

1. Target based on language
Targeting store views using just the language tag is a great method if you cater to a worldwide customer base with different store views in a variety of languages. For example, our webshop's main domain uses English while our Dutch language webshop at uses Dutch.

We set this up as:
[storeview] - hreflang: en
[storeview] - hreflang: nl

For example, the setup for having for Germany and for France would be:

[storeview] - hreflang: en
[storeview] - hreflang: nl
[storeview] - hreflang: de
[storeview] - hreflang: fr

2. Target based on language and region
We have shown above that it is possible to target each storeview based on language. Now, we shall move on to targeting based on region. Using our Dutch storeview at as an example, it is catered towards Dutch speakers. If only a Dutch payment service provider (e.g. iDeal) is available which only residents of The Netherlands are able to use, it would be best to target only people from this country.

Our setup would then be:
[storeview] - hreflang: en
[storeview] - hreflang: nl-nl

If the tag is "nl-nl", the first part of the tag, "nl", represents the language while the second part of the tag "nl" represents the region. This is useful when you only provide local shipping methods in each storeview

The values used in the hreflang attribute follow the ISO 639-1 ( format for language and the ISO 3166-1 Alpha 2 ( format for region, for example:

en-GB: English content, for GB users
fr: French content, independent of region
de-ES: German content, for users in Spain

For example, you can lead all (other) English speakers to a generic English (en) page while English speakers from Ireland (en-ie) paying in Pounds, Canada (en-ca) paying in Canadian Dollars, Australia (en-au) paying in Australian Dollars and England (en-gb) paying in Pounds will be led to a different specific store view.

[storeview] - hreflang: en-ie
[storeview] - hreflang: en-ca
[storeview] - hreflang: en-au
[storeview] - hreflang: en-gb
[storeview] - hreflang: en  

Please note that we are not an SEO agency and or Google advise company. Our extension provide the technical method to automatically add href lang tags for your multi-language store under the Google requirements. You can also read more information about how to setup the HREF Lang Tags for your specific countries on the Google Support and Help Section or ask your SEO agency which configuration is optimal for your Magento store.