JSFiddle - React, Tailwind, and code Playground

HTML

<select onchange="SomeBCfunction(a,b,c);" id="shippingCountry">
    
    <option value="AF">AFGHANISTAN</option>
    <option value="AX">ALAND ISLANDS</option>
    <option value="GB" selected="selected">UNITED KINGDOM</option>
    
    </select>

    <div id="zones">Show message</div>
    <div id="zones1">ốc đảo</div>
    <div id="zones2">Mỹ</div>

JavaScript

$(document).ready(function(){
 
     $('#shippingCountry').on('change', function() {
      if ( this.value == 'GB')
          {
            $("#zones").show();
          }
      else ( this.value == 'AX')
          {
            $("#zones1").show();
          }
      if ( this.value == 'AF')
          {
            $("#zones2").show();  
          }
    });
    });