index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <ul>
        <li>
            Add Favoritos
        </li>
    </ul>
    <style>
        body {
            overflow: hidden;
        }
        ul {
            width: 100%;
            height: 100vh;
            display: flex;
            justify-content: center;
            align-items: center;
        }
        li {
            cursor: pointer;
            position: relative;
            transition: color .3s;
        }
        li::before {
            transition: 5s;
        }
        li:hover::before {
            font-size: 12px;
            font-family: sans-serif;
            position: absolute;
            top: -40px;
            right: -50px;
            content: "Favoritos";
            background-color: rgb(91, 91, 91);
            color: #eee;
            padding: 10px 25px;
        }
    </style>
</body>
</html>