When rabbits feel threatened, they will make a high-pitched "scream". This is a short, sharp noise that is designed to alert other rabbits to danger. Rabbits may also make a soft "cooing" sound when they are feeling content and relaxed. This sound is often accompanied by purring, which is a low, guttural sound that rabbits make when they are happy and comfortable.
Lastly, rabbits also make a grinding sound with their teeth when they are eating or chewing on something. This is a normal sound and does not indicate anything wrong with your rabbit.