> HTML

<div class="tooltip">Hover over me
  <span class="tooltiptext">Tooltip text</span>
</div>

> CSS (LEFT)

.tooltip {
  position: relative;
  display: inline-block;
  border-bottom: 1px dotted black;
}
.tooltip .tooltiptext {
  visibility: hidden;
  width: 120px;
  background-color: black;
  color: #fff;
  text-align: center;
  border-radius: 6px;
  padding: 5px 0;
  position: absolute;
  z-index: 1;
  top: -5px;
  right: 110%;
}
.tooltip .tooltiptext::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 100%;
  margin-top: -5px;
  border-width: 5px;
  border-style: solid;
  border-color: transparent transparent transparent black;
}
.tooltip:hover .tooltiptext {
  visibility: visible;
}

> CSS (RIGHT)

.tooltip .tooltiptext {
    background-color: #394d6b;
    border-radius: 6px;
    color: #fff;
    margin-left: 16px;
    padding: 6px 10px;
    position: absolute;
    text-align: center;
    top: -5px;
    visibility: hidden;
    width: fit-content;
    z-index: 11;
}

.tooltip {
    display: inline-block;
    margin-left: 50px;
    position: relative;
}

.tooltip .tooltiptext::after {
    border-color: transparent #394d6b transparent transparent;
    border-style: solid;
    border-width: 6px;
    content: "";
    margin-top: -5px;
    position: absolute;
    right: 100%;
    top: 50%;
}

.tooltip:hover .tooltiptext {
    visibility: visible;
}