This is a user right. See Special:ListGroupRights for an overview of the rights used on translatewiki.net. See Manual:User rights at MediaWiki.org for general information.
For the corresponding action to this user right, Right-centralauth-merge ("Fusionar a conta propia"), see:
This message uses the singular "they", "their", "them" or "themself" as a gender-neutral pronoun.
This should be translated preserving the singular meaning as fit for your language in a gender-neutral way.
This user right allows the user to use Special:MergeAccount to merge his/her own account with accounts on other projects.
Merge their account
Fusionar a conta propia