"Hola" is a String of 5 characters? Why?

Question

The explanation, in Spanish, says that "Hola" is a String of 5 characters, but Hola only has 4 letters... Am I missing something or it was just a typo?

Answer 1

h-1
0-2
l-3
a-4
last is null character so it is having 5 characters

Answer 2

I see, thank you!!