Hello,
Let’s start with the mistakes:
Javascript is a language case sensitive, that is, the reserved word var will not be interpreted as Var. The same occurs with the Document that should be document and Exemplo that should be exemplo, since you declared him with the D minuscule.
All Javascript code within an HTML code must be within the tag <script></script>.
Knowing this, convert your code to this:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
</head>
<body>
<span id="exemplo"></span>
<script>
var exemplo = 10;
document.getElementById('exemplo').innerHTML = exemplo;
</script>
</body>
</html>
document.getElementById("pontos").innerHTML = exemplo;javascript is case sensitive, beware of uppercase– Ricardo Pontual