Formal:
* Bilingual (in English and French)
* Fluent in both English and French
* Proficient in both English and French
Informal:
* Someone who speaks both English and French
* A bilingual speaker
* An English and French speaker
You can also use more descriptive terms depending on the context, like:
* A French-English speaker (emphasizing the French language)
* An English-speaking French person (emphasizing the person's nationality)
Ultimately, the best term depends on the specific context and the desired level of formality.