file - \components\com_easyblog\themes\wireframe\mediamanager\dialog.create.folder.php
edit -
<input data-folder-name placeholder="<?php echo JText::_('Enter a name for your folder...');?>" class="form-control" />
edit -
<input data-folder-name placeholder="<?php echo JText::_('Enter a name for your folder...');?>" class="form-control" />