Goku was born in age 737 in the mountains of Saiyans. We can only give Goku two ages physically and chronological.
In the development of the Goku serieso there are times Goku’s age would be backtracked, sometimes he would die and stay some years dead but later be raised again. This can then explain Goku’s age in two ways physical age and chronological age. Goku must be now physically 13 but psychologically 51.
Goku is the main character that plays in the Japanese manga “Dragon Ball metaseries”.
Goku is brought in the Dragon Ball manga and anime at the age of around 12 years age. He would say he was 14 years but in Tournament that was corrected. It is said that Goku don’t know how to count correctly. He is unschooled though he is smart. He never went to school due to being born in remote mountains of Mount Paozu.
Goku’s name is is also mystery. It os a combination of two syllable “Go” and “Ku”.
“Go” meaning aware of emptiness and “Ku” means sky or emptiness.
Goku is the idea of Akira Toriyama who wrote the original manga Dragon Boy and Tongpoo. In those mangas, Goku appears initially as a monkey and then as the mangas progressed Goku became human and then human with monkey tail.