Check out example codes for "table with common header for two cells css". It will help you in understanding the concepts better.

Code Example 1

<table>
  <col>
  <colgroup span="2"></colgroup>
  <colgroup span="2"></colgroup>
  <tr>
    <td rowspan="2"></td>
    <th colspan="2" scope="colgroup">Mars</th>
    <th colspan="2" scope="colgroup">Venus</th>
  </tr>
  <tr>
    <th scope="col">Produced</th>
    <th scope="col">Sold</th>
    <th scope="col">Produced</th>
    <th scope="col">Sold</th>
  </tr>
  <tr>
    <th scope="row">Teddy Bears</th>
    <td>50,000</td>
    <td>30,000</td>
    <td>100,000</td>
    <td>80,000</td>
  </tr>
  <tr>
    <th scope="row">Board Games</th>
    <td>10,000</td>
    <td>5,000</td>
    <td>12,000</td>
    <td>9,000</td>
  </tr>
</table>

Learn ReactJs, React Native from akashmittal.com