Q:

Multiple libraries were found for "ESP8266WiFi.h"

I'm trying to use ESP8266 module and i used esp8266wifi.h.
but it doesn't work :( Will you help me?? Here's my codes. I tried to find multiple libraries of "ESP8266WiFi.h", but i couldn't find any of multiple libraries. 
#include "ESP8266WiFi.h"
#include  "WiFiUDP.h"

const char* ssid = "your ssid";
const char* password = "your password";

WiFiUDP Udp;
unsigned int localUdpPort = 4210;
char incomingPacket[255];
char replyPacket[] = "Hi there! Got the message.";

void setup() {

  Serial.begin(115200);

  connectWifi();

  Udp.begin(localUdpPort);

}

void loop() {

  int packetSize = Udp.parsePacket();
  if(packetSize){
    Serial.printf("Received %d bytes from %s, port %d\n", packetSize,         Udp.remoteIP().toString().c_str(), Udp.remotePort());
    int len = Udp.read(incomingPacket, 255);
    if (len > 0)
    {
      incomingPacket[len] = 0;
    }
    Serial.printf("UDP packet contents: %s\n", incomingPacket);

    // send back a reply, to the IP address and port we got the packet from
    Udp.beginPacket(Udp.remoteIP(), Udp.remotePort());
    Udp.write(replyPacket);
    Udp.endPacket();
    delay(1000); // Need a delay otherwise the data is not sent Was 3000
  }

}

void connectWifi(){
  Serial.print("Connecting to ");
  Serial.print(ssid);

  WiFi.disconnect(true);
  delay(1000);
  WiFi.begin(ssid, password);
  while(WiFi.status() != WL_CONNECTED){
    delay(500);
    Serial.print(".");

  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.print("IP Address: ");
  Serial.print(WiFi.localIP());
  Serial.println("");
}

And here's my error messages. And will you tell me what "queue.h" means?? I can't find it.
Arduino: 1.8.10 (Windows 10), Board: "Arduino/Genuino Uno"

Multiple libraries were found for "ESP8266WiFi.h"
In file included from C:\Program Files (x86)\Arduino\libraries\ESP8266WiFi\src/ESP8266WiFi.h:33:0,

 Used: C:\Program
             from C:\Users\user\Desktop\sketch_dec18b\sketch_dec18b\sketch_dec18b.ino:1:

C:\Program Files (x86)\Arduino\libraries\ESP8266WiFi\src/ESP8266WiFiType.h:26:10: fatal error: 
queue.h: No such file or directory

#include <queue.h>

      ^~~~~~~~~

compilation terminated.

exit status 1
Error compiling for board Arduino/Genuino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

A:

You mentioned that you would like to use ESP8266 as a standalone module (not as a secondary MCU, controlled by AT commands) but according to the log, the compiler is trying to translate for Arduino/Genuino Uno board.
I think the first step should be to check the board settings and install the necessary packages, if the required one is not available.
Board settings

