Answer:
Following are the code to this question:
public class Main//defining a class
{
 public static void main(String[] arg)//defining main method 
 {
   String[] words={"Key","day", "Know", "kind"};//defining array of String words
   int x=0;//defining integer variable for count value
   for(int i=0;i<words.length;i++)//defining for loop for count value
   {
  if(words[i].startsWith("k")||words[i].startsWith("K"))//use if block to check word start from k
   x=x+1;//increment the value of x
   }
 System.out.print("The number of letters which starts from k is: "+ x);//print value with message
}
}
Output:
The number of letters which starts from k is: 3
Explanation:
In this code, inside the main method an array of String "words" is defined that hold a value, and in the next step an integer variable "x" is defined, which is used to count the letters, which starts from k. 
For this, a for loop is used that counts the value and in this an, if block is defined that uses the "startsWith" method to check the value and increment the value of x and at the last, it prints its value.