<!DOCTYPE html>

<html lang="en">

<head>

    <meta charset="UTF-8">

    <title>Title</title>

</head>

<body>

<select name="prl" id="prl" onchange="func6(this)">

    <option value="1">a</option>

    <option value="2">b</option>

    <option value="3">c</option>

    <option value="4">d</option>

    <option value="5">e</option>

</select>

<div>

<textarea name="pro" id="pro" cols="30" rows="10"></textarea>

</div>

</body>

<script src="/static/jquery-3.3.1.js"></script>

<script>

    function func6(ths) {

        var data=ths.options[ths.selectedIndex].text

        $('#pro').val(data)

    }

</script>

</html>