SOURCE

let people = document.querySelector(".people")
        let oUl = document.querySelector("ul")
        people.onmouseover = function(){
            oUl.style.display = "block"
        }
        people.onmouseout = function(){
            oUl.style.display = "none"
        }

<div class="people">
  <div class="people-name">
    个人信息 ∨
  </div>
  <ul>
    <li>
      订单信息
    </li>
    <li>
      修改密码
    </li>
    <li>
      退出登录
    </li>
  </ul>
</div>

 * {
   margin: 0;
   padding: 0
 }
 
 .people {
   width: 150px;
   margin: 50px auto;
   text-align: center;
 }
 
 .people-name {
   line-height: 40px;
   border: 1px solid #000;
 }
 
 ul {
   border: 1px solid #000;
   border-top: none;
   display: none;
 }
 
 ul li {
   list-style: none;
   border-top: 1px solid #000;
   height: 36px;
   line-height: 36px;
   cursor: pointer;
 }
 
 li:nth-child(1) {
   border-top: none;
 }