Wiki writes that the giraffe's tongue is blue "probably" to avoid sunburn. What does it mean?

According to the theory, there is an increased amount of melanin in the giraffe's tongue to protect the giraffe, since melanin absorbs more UV rays from the sun, protecting the giraffe from the sun's damage. Some biologists have raised doubts about the theory, but it seems this is the most widely accepted explanation. You can read more about giraffes and blue tongues here:

https://www.sciencefocus.com/nature/why-do-giraffes-have-purple-tongues