what does this ...Array doing in react?

im working on react code and there is ...Array. I saw that it's called spread operator but I can't understand and usage in the below code.

 const rawData= [[7,0,0,1,6,1],[8,2,5,1,7],[5,4,1,4],[2,2,0]]
 
 return (
    <table>
      <thead>
        <tr>
          <th></th>
          <th>Week 1</th>
          <th>Week 2</th>
          <th>Week 3</th>
          <th>Week 4</th>
          <th>Net Lost</th>
          <th>Net Recovered</th>
        </tr>
      </thead>
      <tbody>
        {rawData.map((item, index) => {
          return (
            <tr>
              <th>Week {index + 1}</th>
              {[...Array(6 - item.length)].map((item) => {
                return <td></td>;  //for empty values
              })}
              {item.map((itm) => {
                return <td>{itm}</td>;
              })}
            </tr>
          );
        })}
      </tbody>
    </table>
  );
   
}

There is no defined array called Array and what does [...Array(6 - item.length)] this mean?