diff --git a/core/lib/Drupal/Core/Entity/EntityFieldQuery.php b/core/lib/Drupal/Core/Entity/EntityFieldQuery.php
index 9ba628e..0c054ce 100644
--- a/core/lib/Drupal/Core/Entity/EntityFieldQuery.php
+++ b/core/lib/Drupal/Core/Entity/EntityFieldQuery.php
@@ -428,11 +428,15 @@ class EntityFieldQuery {
    *   The operator can be omitted, and will default to 'IN' if the value is an
    *   array, or to '=' otherwise.
    * @param $langcode_group
-   *   An arbitrary identifier: conditions in the same group must have the same
-   *   $langcode_group.
+   *   (optional) An arbitrary identifier: conditions in the same group must
+   *   have the same group identifier. This is used to group the condition with
+   *   a related set of other property conditions and meta conditions. By
+   *   default all conditions belong to the same group.
    *
    * @return Drupal\Core\Entity\EntityFieldQuery
    *   The called object.
+   *
+   * @see Drupal\entity\EntityFieldQuery::propertyLanguageCondition()
    */
   public function propertyCondition($column, $value, $operator = NULL, $langcode_group = 0) {
     $this->properties[$langcode_group][$column] = $column;
@@ -449,14 +453,39 @@ class EntityFieldQuery {
   /**
    * Adds a condition on the property language.
    *
+   * Since the entity storage controller may support multilingual properties,
+   * there may be cases where different conditions on different languages may be
+   * needed. This method allows to specify which language a particular set of
+   * conditions and order settings should have. For example:
+   * @code
+   *   $query = new EntityFieldQuery();
+   *   $query->entityCondition('entity_type', 'entity_test');
+   *   // Find all English entities.
+   *   $query->entityCondition('langcode', 'en');
+   *   // Having the specified English values for uid and name.
+   *   $query->propertyCondition('uid', $uid, '=', 'original');
+   *   $query->propertyCondition('name', $name, '=', 'original');
+   *   $query->propertyLanguageCondition('en', '=', 'original');
+   *   // And having the specified Italian value for name.
+   *   $query->propertyCondition('name', $name_it, '=', 'translation');
+   *   $query->propertyLanguageCondition('it', '=', 'translation');
+   *   // Order the result set by the English name.
+   *   $query->propertyOrderBy('name', 'ASC', 'original');
+   *   $result = $query->execute();
+   * @endcode
+   * Without specifiying two different language groupings there would be no way
+   * to apply both name conditions, as they would mutually exclude each other.
+   *
    * @param $langcode
    *   The language code that the properties belonging to the language group
    *   should match.
    * @param $operator
    *   The operator to be used to test the given value.
    * @param $langcode_group
-   *   An arbitrary identifier: conditions in the same group must have the same
-   *   $langcode_group.
+   *   (optional) An arbitrary identifier: conditions in the same group must
+   *   have the same group identifier. This is used to group the language meta
+   *   condition with a related set of property conditions. By default all
+   *   conditions belong to the same group.
    *
    * @return Drupal\entity\EntityFieldQuery
    *   The called object.
@@ -565,11 +594,16 @@ class EntityFieldQuery {
    * @param $direction
    *   The direction to sort. Legal values are "ASC" and "DESC".
    * @param $langcode_group
-   *   An arbitrary identifier: conditions in the same group must have the same
-   *   $langcode_group.
+   *   (optional) An arbitrary identifier: order settings in the same group must
+   *   have the same group identifier. This is used to group the property order
+   *   setting with a related set of property conditions, meta conditions and
+   *   other order settings. By default all conditions and order settings belong
+   *   to the same group.
    *
    * @return Drupal\Core\Entity\EntityFieldQuery
    *   The called object.
+   *
+   * @see Drupal\entity\EntityFieldQuery::propertyLanguageCondition()
    */
   public function propertyOrderBy($column, $direction = 'ASC', $langcode_group = 0) {
     $this->properties[$langcode_group][$column] = $column;