moodle-block_mytreestudyplan/lang/en/block_mytreestudyplan.php

<?php
$string['pluginname'] = 'My Treestudyplan';
$string['mytreestudyplan'] = 'MyTreestudyplan';
$string['title'] = 'My Studyplan';
$string['mytreestudyplan:addinstance'] = 'Add my studyplan block';