根据您的评论，我实现了keyframes，它每5秒更改一次元素的内容。
如果您想在动画中添加更多细节，请查看animation

@keyframes change-text {
  0% {
    content: "Hello";
  }
  33.33% {
    content: "Hello 2";
  }
  66.66% {
    content: "Hello 3";
  }
  100% {
    content: "Hello 4";
  }
}

.text-container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.text {
  font-size: 2rem; 
}
.text::after {
  display: block;
  content: "Hello";
/* animation-duration = number of keyframes * duration per keyframe */
  animation: change-text 20s infinite;
}

<div class="text-container">
  <div class="text"></div>
</div>

.yourClass {
    visibility: hidden;
    position: relative;
}

.yourClass:after {
    visibility: visible;
    position: absolute;
    top: 0;
    left: 0;
    content: "The world is so beautiful!";
}

<div class="yourClass">Hello World!</div>