how can i store my array values into multiple rows into database

my table looks like,

id | heading | description
     
 1 | head1,head2   | des1,des2
    

and i want it to be like this,

 id | heading | description
    
 1 | head1   | des1
     
 2 | head2   | des2

Here I am added values into table with ‘add more’ feature in frontend UI. These vales are fetched using array. after applying ‘implode’ method i could store it into a table. But unfortunately that values are stored with comma separated manner in a same row . how can i store these comma separated array values into different row?

UI:

                 <p>Add technical details below</p>

          <label class="label"> <strong> Warishan Names <strong> </label>
<div class="table-responsive">
    <table id="form_tablee" class="table table-bordered">
        <tr>
            <!-- <th>S. No</th> -->
            <th>heading</th>
            <th>Description</th>
        </tr>
        <tr class='case'>
            <!-- <td><span id='snum'>1.</span></td> -->
            <td><input class="form-control" type='text' name='heading[]'/></td>
            <td><input class="form-control" type='text' name='description[]'/></td>
           <input type="hidden" class="prodid" name="id">
        </tr>
    </table>
    <button type="button" class='btn btn-success addmoree'>+ add new field</button> <br>
</div>

<!-- <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.1/css/bootstrap.min.css"> -->

  <script>
$(document).ready(function(){
    $(".addmoree").on('click', function () {
        var count = $('table tr').length;
        var data = "<tr class='case'>";
        data += "<td><input class='form-control' type='text' name='heading[]'/></td> <td><input class='form-control' type='text' name='description[]'/></td></tr>";
        $('#form_tablee').append(data);
        count++;
    });
});
</script>

function:

<?php


    $heading = $_POST['heading'];

    $description = $_POST['description'];
    $id = $_POST['id'];

    if (isset($_POST["heading"]) && is_array($_POST["heading"])){ 
            
            $heading       = $_POST['heading'];
            $heading_str   =implode(",",$heading);
    }

    if (isset($_POST["description"]) && is_array($_POST["description"])){ 
            
            $description       = $_POST['description'];
            $description_str   =implode(",",$description);
    }

    



     $status="1";

    $conn = $pdo->open();



        try{
            
            $stmt = $conn->prepare("INSERT INTO tech (heading ,description ,pro_id) VALUES (:heading , :description ,:pro_id)");
            $stmt->execute(['heading'=>$heading_str,'description'=>$description_str,'pro_id'=>$id]);
            $_SESSION['success'] = ' successfully';
            
    

        }
        catch(PDOException $e){
            $_SESSION['error'] = $e->getMessage();
        }
    


       $pdo->close();
        header('location: products.php');
         ?>