JSFiddle - React, Tailwind, and code Playground

HTML

<table id="tableSample" class="table table-hover table-sindi table-sindi-select sindi-actions">
    <thead>
        <tr>
            <th>Usuario</th>
            <th>Comentario</th>            
        </tr>
    </thead>
    <tbody>
      <tr>
        <td>Usuario 1</td>
        <td>
          Comentario 1
          <span class="showOnHover">!FOCUS</span>
        </td>
      </tr>
      <tr>
        <td>Usuario 1</td>
        <td>
          Comentario 1
          <span class="showOnHover">!FOCUS</span>
        </td>
      </tr>         
    </tbody>
</table>

CSS

.table-hover > tbody > tr:hover > span.showOnHover {
        display:block!important;
    }

    .table-hover > tbody > tr > span.showOnHover {
        display: none !important;
    }