JSFiddle - React, Tailwind, and code Playground

HTML

<ul id="lang">
    <li>Česky</li>
    <ul id="submenu">
        <li>Mongolsky</li>
        <li>Arabsky</li>
    </ul>
</ul>

CSS

ul#lang {
    position: relative;    
}
ul#submenu {
    display: none;
    position: absolute;
    left: 0;    
}
ul#lang:hover>ul#submenu {
    display: block;    
}