SOURCE

<div>
    <button><span>hover</span></button>
</div>

button{
    border: none;
    outline: none;
    color: #fff;
    padding: 20px;
    width: 200px;
    background-color: orange;
    font-size: 28px;
    border-radius: 5px;
    text-align: center;
    cursor: pointer;
    transition: all 0.5s;
    position: relative;
    display: inline-block;
    margin-right: 10px;
}
button>span{
    position: relative;
    display: inline-block;
    transition: 0.5s;
}

button>span::after{
    content: '»';
    position: absolute;
    top: 0px;
    right: -20px;
    opacity: 0;
    transition: 0.5s;
}
button:hover span{
    padding-right: 20px;
}
button:hover span::after{
    opacity: 1;
    right: 0;
}