Tooltip - подсказка html, css.

block.pug

.smallBlock
  a.tooltip-my(href="#" data-tooltip="Никуда не ведет.") Ссылка с подсказкой.
  
  

block.sass

.smallBlock
  border: 1px solid purple
  padding: 50px 10px
.tooltip-my
  position: relative
  display: inline-block
  &::after
    position: absolute
    top: -35px
    right: 40px
    padding: 5px
    font-size: 16px
    color: white
    visibility: hidden
    content: attr(data-tooltip)
    background-color: purple
    opacity: 0
    transition: .3s
  &:hover::after
    visibility: visible
    opacity: 1