法文 and
法语 both mean 'French language,' but
法语 is more commonly used in mainland China to refer to the spoken/written language, while
法文 is more common in Taiwan and formal/written contexts. Compare the pattern:
中文/
英文/
法文/
德文 (Chinese/English/French/German written language) versus
中语/
英语/
法语/
德语.
