The ‘Share slugs’ feature is available in Polylang Pro. For this feature to be activated, you need to use pretty permalinks and the language must not be set from the content.
This feature allows you to share the same slug between the translations for all types of content, pages, posts, categories, tags, media, custom taxonomies… The example shown below is for tags but it works the same way for the other types of content.
Here the tag ‘Paris’ was created in English then in French. The default slug created by WordPress is ‘paris’ for both languages.
Note: It’s a known issue that when using the WordPress Importer plugin, the content having a shared slug is not imported.
Note: If you deactivate Polylang, only one tag among all sharing the same slug will be displayed.