Multiplication in Nested For Loops

Can someone please explain this function and it operation for my understanding. I came a crossed this exercise and I did it perfectly but, I am still having problem understanding how the 30 resulted in the console output. The parameter replacement value are nested array which index are 1, 3, and 5. The variable age is multiple by the parameter as display in the code below. A brief explanation over the code below will be a great help.

const jboy =function(am){
  let age = 2;
  for(let k = 0; k < am.length; k++){
    for(let ek = 0; ek < am[k].length; ek++){
      age = age * am[k][ek];
    }
  }
  return age;
};

console.log(jboy([[1], [3], [5]])) // output = 30

I tried understanding the above code and it operation but, I still have some holes in my foundation.