What kinds of line is “busted line”?
"It's busted lines" might be a bit confusing to understand. "It's" here should be understood as "it has," "busted" can mean "broken open" or "smashed," and "lines" can be understood as "cracks." Thus, we might interpret the sentence to mean that smashing the coconut has caused it to have cracks along its surface, thereby making it easier to open. Ex: The coconut shell was cracked and had many lines running along its surface. Ex: The man easily busted open the coconut shell.