Master Roshi’s kanji – 亀
Master Roshi’s kanji pronounced kame and meaning “turtle”, is the kanji that all of those trained under Master Roshi are given to wear after completing their training. This kanji is a patch worn on the top left side of the Turtle School uniform, and on a much larger patch on the back.
King Kai’s kanji – 界王
King Kai’s kanji pronounced kaiō and meaning “world king” King Kai wears these two kanji on a large, round patch on the front of his uniform. When Goku dons it, he wears it only on the back of his uniform, keeping the Turtle School’s kanji on the top left of the front of his uniform. Yamcha wears it in reverse to Goku, having the Kai kanji on the front and the Turtle kanji on the back.
Goku’s kanji – 悟
Goku‘s kanji pronounced Go (meaning “wisdom” or “enlightenment”) is the kanji that Goku sports on both the front and back of his uniform after completing his intense gravity training inside his spaceship on his way to Namek. Goku continues to wear this kanji until the arrival of the Androids, after which he stops wearing a kanji altogether.
This is the symbol of Whis, which also signifies him becoming the teacher of Goku and Vegeta.
Bonus : It’s about Royal Crest Symbol And Gohan’s Symbol.
Saiyan Royal Crest Symbol
The Saiyan Royal Family symbol worn by those of Saiyan royal blood. This symbol appears painted into the armor that is worn by King Vegeta and his son, Vegeta.
Goku’s family kanji – 孫
Goku’s family kanji pronounced son and meaning “descendant”, stands for the families’ surname (Son Goku). Gohan wears this patch in early Dragon Ball Z as a large patch on the front of his tunic.
Gohan’s kanji, 飯 pronounced han and meaning “meal” or “boiled rice”. Future Gohan, the alternate timeline counterpart of Gohan dons this kanji as a large patch on his back.