webstorm: what does "Element is not exported" warning mean? : <p>if i write such code in webstorm </p>

<pre><code>export class someOne {
  constructor(param) {
    this.test = param;
  }

  useTest(){
    return this.test;
  }
}


console.log(new someOne(123).useTest());
</code></pre>

<p>and mouseover on "this.test" i see the warning: "Element is not exported"</p>

<p><a href="https://i.stack.imgur.com/UPh9s.png"><img src="https://i.stack.imgur.com/UPh9s.png" alt="element is not exported wtf"></a></p>

<p>what does it mean?
if i change the <code>.test</code> to <code>.test1</code> the warning disappears</p>
