Make sure to incorporate the Font Awesome (FA) CSS into your HTML file and utilize
<i class="fas fa-angle-right">
to insert the arrow icon.
fa or fas = Font Awesome Solid
far = Font Awesome Regular
fal = Font Awesome Light
fab = Font Awesome Brands
<i class="fa fa-camera-retro"></i> <!-- version 4's format -->
<i class="fas fa-camera-retro"></i> <!-- version 5's format -->
<i class="far fa-camera-retro"></i> <!-- example: regular style of camera-retro -->
<i class="fal fa-camera-retro"></i> <!-- example: light style of camera-retro -->
<link href="https://use.fontawesome.com/releases/v5.8.1/css/all.css" rel="stylesheet"/>
<a class="carousel-control-prev" href="#my-slider" role="button" data-slide="prev">
<span class="carousel-control-prev-icon" aria-hidden="true"></span>
<span>Previous</span>
</a>
<a class="carousel-control-next" href="#my-slider" role="button" data-slide="next">
<span class="carousel-control-next-icon" aria-hidden="true"></span>
<span><i class="fas fa-angle-right"></i> Next</span>
</a>