There are a LOT of things, as in physical things you can do in a scene. Sometimes there will be things written, sometimes, not.
Something like, "HE TAKES A DRINK OF WATER." May seem like simple direction, but they can be much, much more.
If there's some kind of action written into the scene, it's there because the author had something very specific in mind for what that character was feeling in that moment. There's a very specific reason that HE TAKES A DRINK OF WATER right then, and not the line before or after it.
What's the reason?
Damned if I know.
Get creative. it could be a litany of reasons...maybe...
...he needed a minute to think
...he wanted to let the guy think about what he said
...he needs to relax
...he was actually thirsty
These are four off the top of my head. I haven't even seen the scene we're talking about.
If there's stage direction, sure, do the literal thing, sometimes that's all you need. But in the whole play/movie, the guy only ever is directed, in the script, to drink twice, why is this one of the times? You answer that, and you've got a little clue to the character, even if you don't have all the info you'd like on them.