Removing odd symbols from web scraped text

There is content that is web scraped and stored in a JSON string retrieved using the script

$response = response($jsonData)->header('Content-Type', 'application/json');

I then use the following scripts to extract the JSON content and decode the string

    $jsonData = $response->getContent();
    $decodedData = json_decode($jsonData);

The problem is the text is the string has odd text like u2019 and u2018 which seem to be replacing some punctuation marks. What are these and how can I remove them?