JSFiddle - React, Tailwind, and code Playground

HTML

<ul class="icons"><!--ICONS-->
    <li class="oneLI">one<span class="one">Popup for one.</span></li>
    <li class="twoLI">two<span class="two">Popup for two.</span></li>
</ul>

CSS

li {
    position: relative;
}

li span {
    display: none;
    position: absolute;
    left: 30px; bottom: 80%;
    background-color: yellow;
    z-index: 1;
}

li:hover span {
    display: block;
}