
<style>

.dropdown-menu li {
position: relative;
}
.dropdown-menu .dropdown-submenu {
display: none;
position: absolute;
left: 100%;
top: -7px;
}
.dropdown-menu .dropdown-submenu-left {
right: 100%;
left: auto;
}
.dropdown-menu > li:hover > .dropdown-submenu {
display: block;
}

</style>

<nav class="navbar navbar-expand-lg bg-body-tertiary">
  <div class="container-fluid">
    <ul class="navbar-nav">
      <!-- Dropdown -->
      <li class="nav-item dropdown">
        <a data-mdb-dropdown-init class="nav-link dropdown-toggle" href="#"
          id="navbarDropdownMenuLink" role="button" data-mdb-toggle="dropdown" aria-expanded="false">
          Dropdown link
        </a>
        <ul class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <li>
            <a class="dropdown-item" href="#">Action</a>
          </li>
          <li>
            <a class="dropdown-item" href="#">Another action</a>
          </li>
          <li>
            <a class="dropdown-item" href="#">
              Submenu &raquo;
            </a>
            <ul class="dropdown-menu dropdown-submenu">
              <li>
                <a class="dropdown-item" href="#">Submenu item 1</a>
              </li>
              <li>
                <a class="dropdown-item" href="#">Submenu item 2</a>
              </li>
              <li>
                <a class="dropdown-item" href="#">Submenu item 3 &raquo; </a>
                <ul class="dropdown-menu dropdown-submenu">
                  <li>
                    <a class="dropdown-item" href="#">Multi level 1</a>
                  </li>
                  <li>
                    <a class="dropdown-item" href="#">Multi level 2</a>
                  </li>
                </ul>
              </li>
              <li>
                <a class="dropdown-item" href="#">Submenu item 4</a>
              </li>
              <li>
                <a class="dropdown-item" href="#">Submenu item 5</a>
              </li>
            </ul>
          </li>
        </ul>
      </li>
    </ul>
  </div>
</nav>