Create dropdowns to group content in an overlay that can be toggleable via a button. Down you can see an example for a typical dropdown, check the Boostrap documentation for accessability information, how to create split dropdowns and more.

<div class="dropdown">
    <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
        Dropdown button
    <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
        <a class="dropdown-item" href="#">Action</a>
        <a class="dropdown-item" href="#">Another action</a>
        <a class="dropdown-item" href="#">Something else here</a>