Language bar is the one which helps you to switch between languages when you view documents, when you type something using word or open office etc.
Normally East Asian languages like Japanese, Chinese fonts are not installed in your system. You can install them by following the following instructions:
Go to the control panel.
In the control panel select Regional and Language options.
Go to the language Tab.
Check the check box “Install fonts for East Asian languages”. The size of the installation will be shown. Give Ok. Now click the apply button.
A prompt will be given to insert your windows XP CD.
Insert the windows CD and then these East Asian languages will be installed.
From now on you will be able to see a language Bar at the bottom in taskbar. It will help you to switch between languages while typing.