Rewrite: example.com/english/news (URL) => /english/index.php (internal filepath)
RewriteRule ^english/news/$ /english/news.php [L]
More general pattern would be:
RewriteRule ^([^/]+)/([^/]+)/$ /$1/$2.php [L]
Personally, I would NOT use a trailing slash on these URLs. I would use 'extensionless' /english/news instead.
You also need to add the redirect from .php URLs (and it should redirect for both www and non-www) to extensionless URLs (and it should force www for those requests in the same redirect).