It seems to say, 'uunn'.
Which of the four people do you think the message is about?
The message does not necessarily look the same now as it did when it was written.
The sand is on a beach.
Something seems to have made part of the message disappear.
Waves lapping up on the beach have made the top half of the message disappear.
Look at what is left of the letters and try to work out what they were originally.
The three letters on the right are lower case.
The answer is '3'.