Code line explain

Hi guys
Can any one explain to me what is the meaning of the code line sec%60?
The code attached making a count down but im not getting the part of the "sec%60 "

Thanks

int min = 1;
int sec = 30;
unsigned long oneSecond = 1000UL;
unsigned long startTime;

void setup(){  
  Serial.begin(9600); 
  sec = sec + 60 * min;
}
//----------------------------------------------------
void loop()
{
  if (millis() - startTime >= oneSecond)
  {
    sec--;
    startTime += oneSecond;
    if (sec < 0) KaBoom();
    int displayMin = sec/60;
    if (displayMin < 10) Serial.print("0");
    Serial.print(displayMin);
    Serial.print(":");
    int displaySec = sec % 60;
    if (displaySec < 10) Serial.print("0");
    Serial.println(sec % 60);
  }
}
void KaBoom()
{
  Serial.println("The world has ended");
  while(1)
  {
    
  }
}

sec % 60 gives the remainder of sec / 60

I know what is % but ib this code spesific it wont make sense to me
When the sec will get down to 59 why i need to make the %60??

THANKS!

Delta_G:
minutes = sec / 60 == 1
seconds = sec%60 == 6

Should the operations be in the reversed order and with more completeness? although, we are getting correct result in this simple case.

int sec;
int int displaySec = sec%60;
sec = sec/60;
//-------------
int displayMin = sec%60;
sec = sec/60;

Let us take the example of int x = 0x12CD, and we are interested to find its decimal value using % and / operations:

void setup()
{
  Serial.begin(9600);
  byte index[4];
  char decNumber[5];
  int x = 0x12CD; //4813
  
  for (int i = 3; i >= 0; i--)
  {
    index[i] = x % 10;
    x = x / 10;
  }
  
  for (int i = 0; i < 4; i++)
  {
    decNumber[i] = index[i] + '0';
  }
  decNumber[4] = 0x00;      //null-byte
  Serial.print(decNumber);  //shows: 4813

}

void loop() 
{
  
}