The translation was expanded

lang/en/local_billingpatch.php

@@ -22,4 +22,5 @@
  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
 
+$string["billing"]    = "Billing";
 $string["pluginname"] = "System of patches for billing";

lang/ru/local_billingpatch.php

@@ -0,0 +1,25 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Strings for component 'local_billingpatch', language 'ru'.
+ *
+ * @package   local_billingpatch
+ * @copyright 2017 "Valentin Popov" <info@valentineus.link>
+ * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+$string["billing"] = "Биллинг";