I am a newbie to both FreeRTOS and STM32. I want to know how exactly callback function HAL_UART_TxCpltCallback for HAL_UART_Transmit_IT works ? Can we edit that that callback function for our convenience ?

This has nothing to do with my program, can I change this?

 __weak void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
 /* Prevent unused argument(s) compilation warning */
 UNUSED(huart);
 /* NOTE: This function Should not be modified, when the callback is needed,
 the HAL_UART_TxCpltCallback could be implemented in the user file
 */ 
}