Formal:
* Il y a une réunion. (This is the most literal and common translation)
* Une réunion a lieu. (This emphasizes that the meeting is happening)
Informal:
* Il y a un meeting. (This uses the English word "meeting" directly, which is acceptable in some contexts)
* On se retrouve. (This means "We are meeting" and is more informal)
Specific situations:
* Il y a un rendez-vous. (This is used for a scheduled meeting with a specific person)
* Il y a une assemblée. (This is used for a formal gathering of people)
The best translation will depend on the specific context and the level of formality you want to achieve.