需要在data- xxx 属性 中定义内容，可动态设置，这样每次hover时，就会出现提示信息。

html代码：

<div class="box">
    <span data-tip="Hi word!">
        hellow  word!
    </span>
</div>

.box {
    margin-top: 50px;
}

.box span {
    position: relative;
    cursor: pointer;
}

.box span:hover::after {
    content: "";
    position: absolute;
    top: -10px;
    left: 30px;
    width: 0;
    height: 0;
    border-top: 5px solid red;
    border-left: 5px solid transparent;
    border-right: 5px solid transparent;
}

.box span:hover::before {
    content: attr(data-tip);
    background-color: red;
    color: #FFFFFF;
    padding: 4px;
    text-align: center;
    position: absolute;
    top: -39px;
    left: 20px;
    border-radius: 5px;
}