How to combine 2 codes

I created a blinker code and a momentary push button activating a relay for a 12 v horn code to make a UTV street legal.

The problem is when I try to combine them together I receive errors.

The error code I get is

Arduino: 1.8.5 (Windows 10), Board: “Arduino/Genuino Uno”
C:\Users\Matt\Documents\Arduino\ZachTurn_Signal\ZachTurn_Signal.ino\ZachTurn_Signal.ino.ino: In function ‘void loop()’:
ZachTurn_Signal.ino:41: error: ‘TurnOn’ was not declared in this scope
TurnOn(lftLED);
^
ZachTurn_Signal.ino:46: error: ‘TurnOn’ was not declared in this scope
TurnOn(rtLED);
^
ZachTurn_Signal.ino:50: error: a function-definition is not allowed here before ‘{’ token
{
^
ZachTurn_Signal.ino:63: error: expected ‘}’ at end of input
}
^
exit status 1
‘TurnOn’ was not declared in this scope
This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.

How do I combine codes successfully?

Thank You

const int lftSW = 2;  // Left Switch is on pin 2 of Arduino

const int rtSW = 3;   // Right Switch is on pin 3 of Arduino

const int lftLED = 10; //  Left LED Circuit is on pin 10 of Arduino

const int rtLED = 12;   // Right LED Circuit is on Pin 12 of Arduino

const int button1 = 4;         
const int relay1 =  11;           

int buttonState1 = 0;    

void setup() {

  pinMode(relay1, OUTPUT);
  pinMode(button1, INPUT_PULLUP); 
  pinMode (lftSW, INPUT_PULLUP);
  pinMode (rtSW, INPUT_PULLUP);
  pinMode (lftLED, OUTPUT);
  pinMode (rtLED, OUTPUT);

}

void loop()
{
  
 
  buttonState1 = digitalRead(button1);
  
  if (buttonState1 == LOW) {                    
    digitalWrite(relay1, LOW);                    
    delay (1000);                                 
  } else {                                        
    digitalWrite(relay1, HIGH);                  
    }
    
{
  if (digitalRead(lftSW) == LOW)
  {
    TurnOn(lftLED);
  }
  
if (digitalRead(rtSW) == LOW)
{
  TurnOn(rtLED);
}
}
void TurnOn(int led)
{
  for (int i=0;i<3;i++) // Flash Lights 3 times then delay
  {
    digitalWrite(led, HIGH);
    delay(150);

    digitalWrite(led, LOW);
    delay(150);

  }
  delay(150);

}
  }

utv_V4.ino (737 Bytes)

Horn.ino (541 Bytes)

Please change the quote tags in your post to code tags.

Please post your attempt of merging the codes (use code tags) and the resulting complete (!) error message; when errors occur, the top of the output window has a button labeled copy error (or something like that).