Trying to pass selected value from dropdown and substituting in path for redirection

React state updates are asynchronously processed, so you can't enqueue a state update and expect to use the updated result state value within the same render cycle/callback scope. Just use the current label value from the onChange event to form the next target path value. Add a leading "/" so the link is treated as an absolute path, i.e. "/inventory/cluster/" + e.label.

function Cluster() {
  var clusters = [
    {
      value: 1,
      label: "NA1"
    },
    {
      value: 2,
      label: "NA2"
    },
    {
      value: 3,
      label: "NA3"
    },
    {
      value: 4,
      label: "NA4"
    }
  ];

  const history = useHistory();
  const [result, ddlvalue] = useState(clusters[0].label);

  const routeChange = (e) => {
    ddlvalue(e.label);
    let path = "/inventory/cluster/" + e.label;
    console.log(path);
    history.push(path);
  };
  return (
    <div>
      <Select options={clusters} onChange={routeChange} />
      <h1>{result}</h1>
    </div>
  );
}