Can some one explain me this code

void data()
{
// put your main code here, to run repeatedly:
if(ESPserial.available()) // check if the esp is sending a message
{
if(ESPserial.find("+IPD,"))
{
delay(1000);

 int connectionId = ESPserial.read()-48; // subtract 48 because the read() function returns
                                         // the ASCII decimal value and 0 (the first decimal number) starts at 48
 //Display.print(connectionId);


 String cipSend = "AT+CIPSEND=";
 cipSend += connectionId;
 cipSend += ",";
 cipSend +=webpage.length();
 cipSend +="\r\n";

 sendData(cipSend,1000,0);
 sendData(webpage,1000,0);

 //webpage="<h2>Open</h2>";

 //cipSend = "AT+CIPSEND=";
 //cipSend += connectionId;
 //cipSend += ",";
 //cipSend +=webpage.length();
 //cipSend +="\r\n";

 //sendData(cipSend,1000,0);
 //sendData(webpage,1000,0);

 String closeCommand = "AT+CIPCLOSE=";
 closeCommand+=connectionId; // append connection id
 closeCommand+="\r\n";

 sendData(closeCommand,3000,0);
}

}

}

String sendData(String command, const int timeout, boolean debug)
{
String response = “”;

ESPserial.print(command); // send the read character to the esp8266

long int time = millis();

while( (time+timeout) > millis())
{
  while(ESPserial.available())
  {

    // The esp has data so display its output to the serial window
    char c = ESPserial.read(); // read the next character.
    response+=c;
  }
}

if(debug)
{
  Serial.print(response);
}

return response;

}

this is a code to send some information to a web browser . i dont understand it .