Hey there! I'm happy to help!
Giraffes are infamous for not having a memorable sound. Lion is roar, cow is moo, etc. Many studies have shown that giraffes make specific sounds that humans can't really hear, such as a hum or a vibration. They can make other bodily noises such as a snort or grunt.
Research shows that some of these possible noises are a method of communication, but there is still a lot of research going on with this subject.
I hope this helps! Have a wonderful day! :D