index.php

<?php
 $start_word = 'hello';
 $end_word = 'world';
 echo "Start word: ". $start_word . "<br />";
 echo "End word: ". $end_word . "<br />";
 echo "Running the test.py...";
 echo "</br>";
 $output = exec("python test.py ".$start_word." ".$end_word);
 echo 'output from python script: ';
 var_dump( json_decode($output, true));
?>

test.py

#!/usr/bin/env python
import sys, json

print('Number of arguments: ')
print(len(sys.argv))
print('arguments.')
print('Argument List:')
print(str(sys.argv))
result = {'status' : 'Yes!'}

print(json.dumps(result))

Save these files in a folder.
then go to the folder from CMD and type : php -S localhost:8001
Now in the browser open : http://localhost:8001
Also make sure that both python and php are set in the environment variable.
Leave comment if you still need any clarification.
You shoud see:
Start word: hello
End word: world
Running the test.py...
output from python script: array(1) { ["status"]=> string(4) "Yes!" }