<ul class="list-group">
<!-- justify-content-betweenで左と右端にする -->
<!-- align-items-centerで縦整列にする -->
<li class="list-group-item d-flex justify-content-between align-items-center">
リスト項目1
<span class="badge badge-primary badge-pill">14</span>
</li>
<li class="list-group-item d-flex justify-content-between align-items-center">
リスト項目2
<span class="badge badge-primary badge-pill">2</span>
</li>
<li class="list-group-item d-flex justify-content-between align-items-center">
リスト項目3
<span class="badge badge-primary badge-pill">1</span>
</li>
</ul>