Hi Nidhim,
Could you please help us with more details about your print interface?
Just to confirm, are you using the FRDM-KW38 or is it a custom board?
The FRDM-KW38 EVB OpenSDA Interface routes pin 42 (LPUART0_RX) and pin 43 (LPUART0_TX) to an USB interface, which makes the console printing (on your PC) possible using this interface as source when connecting the board via USB (J11).
If your application is intended to print data in console (on your PC), and UART pins need to be changed (for example, to pin 38 and pin 39), you may need to implement an external UART to USB converter when using UART for serial printing.
Also, if you are using a SDK example project, please note that UART should be selected in Project Options when importing the example:

Regards,
Eduardo.