Вот, пожалуйста.Просто добавьте float: right;в сторону уль ли
aside ul {
list-style: none;
position: fixed;
top: 50%;
right: -5px;
overflow: hidden;
-webkit-transform: translateY(-50%);
transform: translateY(-50%);
font-size: 1vw;
}
aside ul li a {
display: block;
height: 5vh;
width: 5vw;
border-radius: 5vh 0 0 5vh;
border: 0.12vw solid #000;
background: #FFF;
margin-bottom: 1vh;
transition: all .4s ease;
color: #2980b9;
text-decoration: none;
line-height: 5vh;
position: relative;
float: right;
}
aside ul li a:hover {
cursor: pointer;
width: 10vw;
color: #fff;
}
aside ul li a:hover span {
left: 3vw;
}
aside ul li a span {
padding: 0 2vw 0 1vh;
position: absolute;
right: -20vw;
transition: left .4s ease;
}
aside ul li a i {
position: absolute;
top: 50%;
left: 1vw;
-webkit-transform: translateY(-50%);
transform: translateY(-50%);
}
aside ul li .facebook {
background:rgba(59, 88, 151, 0.4);
border-color: #3B5998;
color:#3B5998;
}
aside ul li .facebook:hover {
background: #3B5998;
}
aside ul li .github {
background: rgba(117, 117, 117, 0.4);
border-color: #767676;
color: #767676;
}
aside ul li .github:hover {
background: #767676;
}
aside ul li .instagram {
background: rgba(187, 42, 141, 0.4);
border-color: #bc2a8d;
}
aside ul li .instagram:hover {
background: #bc2a8d;
}
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.0.13/css/all.css" integrity="sha384-DNOHZ68U8hZfKXOrtjWvjxusGo9WQnrNx2sqG0tfsghAvtVlRW3tvkXWZh58N9jp"
crossorigin="anonymous">
<aside>
<ul>
<li>
<a href="#" class="facebook">
<span>Facebook</span>
<i class="fab fa-facebook-f text-white"></i>
</a>
</li>
<li>
<a href="#" class="github">
<span>GitHub</span>
<i class="fab fa-github text-white"></i>
</a>
</li>
<li>
<a href="#" class="instagram">
<span>Instagram</span>
<i class="fab fa-instagram text-white"></i>
</a>
</li>
</ul>
</aside>