Increment a char?? I'm confused, please help..

Hello, I'm doing this exercise but I'm totally lost again. It says I'm supposed to create a tileCount and increment it if it matches. For starters, I have never played scrabble so I have no clue how it works. Usually i would just increment as following

int increment = 0; increment++;

Anyhow, here's the exercise description in case you can't see it:

So back to that ScrabblePlayer. I found that it's not enough to know if they just have a tile of a specific character. We need to know how many they actually have. Can you please add a method called getTileCount that uses the for each loop you just learned to loop through the characters and increment a counter if it matches? Return the count, please, thanks!

However, I can't increment a char, and I can't convert an int to a char either, as far as I've learned. I have to return a char however, confused. Help is appreciated. =)

public class ScrabblePlayer {
  private String mHand;

  public ScrabblePlayer() {
    mHand = "";
  }

  public String getHand() {
   return mHand;
  }

   public char getTileCount() {
   char tileCount = '';
   for(char currentTile : mHand.toCharArray()) {
     if(mHand.indexOf(currentTile) >= 0) {
      tileCount++; 
     } 
   }
    return tileCount;
  }

  public void addTile(char tile) {
    // Adds the tile to the hand of the player
    mHand += tile;
  }

  public boolean hasTile(char tile) {
   return mHand.indexOf(tile) > -1;
  }
}