SHOW SOURCE HIDE SOURCE

CSS:

amp-accordion section[expanded] .show{display:none}amp-accordion section:not([expanded]) .hide{display:none}amp-accordion section:not([expanded])>h4{background:green;color:#fff}amp-accordion section[expanded]>h4{background:tomato;color:#fff}

<amp-accordion disable-session-states>
  <section>
    <h4>
      <span class="show">Show/Tampilkan</span>
      <span class="hide">Hide/Sembunyikan</span>
    </h4>
    <p>Hello World! Have a nice day!</p>
  </section>
</amp-accordion>

Show/Tampilkan Hide/Sembunyikan

Hello World! Have a nice day!