Ability to translate English text to another language. The text could be short strings from the Drupal user interface, such as text from buttons and form field names, or it could be technical documentation. In all cases, the source text is in English, and it needs to be translated into another language.
Learning/improvement resources: 

Localize.drupal.org, the service used by translators from around the world to maintain localizations of all projects on drupal.org

Translation guidelines for user interface text provides basic guidelines which can be good starting points in translating Drupal to your own languag

Overview of Localize.drupal.org

User interface translation on localize.drupal.org

Demonstrated by: 

A Skilled translator should be able to do the following:

  • Understand the source text in English in context
  • Translate the English text into the target language, getting across its full meaning
  • Write clearly in the target language
  • Know how to use the tools at localize.drupal.org

An Expert translator should additionally be able to do the following:

  • Have a near-native-level understanding of both English and the target language
  • Have excellent technical writing skills in the target language
  • Be able to review translations provided by others to verify that the source and target language versions really match
  • Be very familiar with the tools used for translating

Roles and Tasks that require this skill

Review a translation (Contributor task)
Review new and updated translations by new translators so they can be accepted into the localization system
Duration: 20 minutes
Translate user interface text (Contributor task)
Propose one or more translations of user interface text, from English to a non-English language
Duration: 1 hour
Translation group manager (Contributor role)
Oversee the translators and translation moderators for a language
Duration: ongoing
Translation moderator (Contributor role)
Review new and updated translations, marking them either as approved or rejected
Duration: ongoing
Translator (Contributor role)
Translate English text that is part of the Drupal and contrib module codebase into other languages
Duration: ongoing

Roles and Tasks that may use this skill

Mentor (Contributor role)
Inspire, enable, and encourage new core contributors. Work on the core tools and process for mentoring
Duration: several hours
Review a translation (Contributor task)
Review new and updated translations by new translators so they can be accepted into the localization system
Duration: 20 minutes
Translate user interface text (Contributor task)
Propose one or more translations of user interface text, from English to a non-English language
Duration: 1 hour
Translator (Contributor role)
Translate English text that is part of the Drupal and contrib module codebase into other languages
Duration: ongoing