In Salesforce Apex, you can generate a random string using the following code:

      
private static String generateRandomString(Integer len) {
        final String chars = 'xaxPmno2IDdEwLzbtEvhv6oG1RDT6xQJX3MvF4amaDQ9TUvHgJfdbodlllPTnnuw';
        String randStr = '';
        while (randStr.length() < len) {
            Integer idx = Math.mod(Math.abs(Crypto.getRandomInteger()), chars.length());
            randStr += chars.substring(idx, idx+1);
        }
        return randStr;
    }
      
    

You can call this function by passing in the desired length of the string, like this:

String randomString = generateRandomString(10);