In the series, "Kakarot" is the Saiyan name given to Goku at birth. It's a common Saiyan name, similar to how Earthlings have names like "John" or "Mary."
The name "Kakarot" has no specific meaning in the Dragon Ball universe. It's simply a name that was chosen for the character.
However, the name "Goku" is based on the Japanese word "孫悟空" (Son Gokū), which is a Chinese legend about a mischievous monkey who gains supernatural powers.