problem in serial communication receiving some random veriable

void setup()
{
  pinMode(13,OUTPUT);
  Serial.begin(9600);
  //Serial1.begin(9600);
  delay(1000);
  digitalWrite(13,LOW);
}
void loop()
{
  if(Serial.available()>0)
  { 
    digitalWrite(13,HIGH);
    int x = Serial.read();
    Serial.println(x,DEC);
  }
  digitalWrite(13,LOW);
}

send an integer value serialy throuugh serial monitor but displayed "49 10 " in serial monitor while displayed the received value

Carriage return is not random.
It always has the decimal value 10

Edit oops, it’s line-feed, not carriage return. Brain fart.

You're printing the ascii code of the character (49 is 1, 50 is 2 etc): change the Serial.print to a Serial.write.

Then the 10 is the ascii newline (aka line feed): switch to no line ending in the bottom right of the monitor.

AWOL:
Carriage return is not random.
It always has the decimal value 10

LF is 10, CR is 13

(CRLF pair is embedded in my mind as ascii 0D0A in years’ worth of hex dumps.)