JSFiddle - React, Tailwind, and code Playground

HTML

<a href="#">
<div class="portfolio_bg">
  <img src="https://www.w3schools.com/howto/img_avatar.png" alt="Avatar" class="portfolio_image">
  <div class="portfolio_caption">This is the text that I want to hide when the mouse is hovered but it doesn't go away!</div>
  <div class="portfolio_overlay">
    <div class="portfolio_text">Hello World and the whole kind of thing goes down!</div>
  </div>
</div>
</a>

CSS

.portfolio_bg {
  position: relative;
  width: 50%;
}

.portfolio_image {
  display: block;
  width: 100%;
  height: auto;
}

.portfolio_overlay {
  position: absolute;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  height: 100%;
  width: 100%;
  opacity: 0;
  transition: .5s ease;
  background-color: rgba(104, 120, 129, 0.5);
}

.portfolio_bg:hover .portfolio_overlay {
  opacity: 1;
}


.portfolio_bg:hover .portfolio_caption {
  opacity: 0;
}


.portfolio_caption {
  color: white;
  font-size: 20px;
  position: absolute;
  bottom: 10%;
  left: 10%;
}
.portfolio_caption:hover {
  opacity: 0;
  display: none;
}

.portfolio_text {
  color: white;
  font-size: 20px;
  position: absolute;
  bottom: 10%;
  left: 10%;
}