Hi Dave,
Short answer is fsl_debug_console() is reduced functionality IO calls in source code for replacing bulky library calls printf/scantf/putchar/getchar. The fsl_debug_console.h has following:
int debug_printf(const char *fmt_s, ...);
int debug_putchar(int ch);
int debug_scanf(const char *fmt_ptr, ...);
int debug_getchar(void);
So once you configure the Component for a particular UARTx, then the above function calls will use that UARTx.
ex: debug_printf("\nHello World");
unsigned char single_char=1;
debug_printf("%d", single_char);
Slightly old (but not too old) document to show how it is configured into a KSD/KSDK/PE/MQX project:
How To: Create an MQX RTOS for KSDK project with Processor Expert in Kinetis Design Studio IDE
Regards,
David