JSFiddle - React, Tailwind, and code Playground

HTML

<div class="first"></div>
<div class="second"></div>

CSS

.first {
    width: 100px;
    height: 100px;
    background-color: gray;
}

.first:hover ~ .second {
    display:block;
}

.second {
    width: 100px;
    height: 100px;
    background-color: red;
    display:none;
}