How id Luke understand R2D2?

In A New Hope, it's clear that Luke doesn't unederstand R2D2 when R2 speaks, but et in TESB & ROTJ, he seems to understand what R2's saying. He R2 will beep & Luke will respond, even asnwering a few questions. How come? Hoiw come he can't understand him in ANH, but he can in TESB & ROTJ?

I've always wondered this. I like to imagine that R2 units transmit on a frequency and they keep adjusting that frequency until it suits your ears and your brain can compute what is being transmitted. Therefore it might take a little time.

He doesn't really understand R2. Check out this line: "If you're saying that coming here is a bad idea, I'm beginning to agree with you." Luke is using him to reflect his own thoughts.

That line sounds more like R2 was insinuating something with his tone--something even the audience should catch on to.

Maybe its a jedi/force thing.

Droid is actually a language people can learn. It's kinda like Shirriwook. You can learn it, but never speak it.

Luke took a crash course in Droid on Tatooine. It was the only form of education that planet had, other than sand curation.

Luke doesn't understand R2 in ESB or ROTJ

In ESB, When Luke is on his way to see Yoda in his ship, "I have a promise to keep, to an old friend". Luke reads what R2 is saying off a computer screen in his ship after he left Hoth. This is the only time they have a conversation.

Luke talks to a droid on Degobah but doesn't need to understand exactly what R2 is saying

Indeed.

luke spoke parcel tongue, as do droid mechanics its why the serpent in the trash bin of the death star targeted him. Yep people don't realize that the leader of the sith was on tatooine his name was Lord Riddle, he was a secret sith that would later be warped into earth future by sidious.

I always thought that, at least while they were flying the X-wing ship, there was a sort of translator that Luke read to see what R2 was saying. He never really held a back and forth with the droid outside of the fighter. At least I don't remember that every happening.

In fact, if you watch ESB, when Luke tells R2 that they're not meeting up with the rest of the fleet in favor of going to Degobah it seems that we're quickly able to see a screen on the X-Wing's console that seems to translate R2's beeps. I could be wrong about that, though.

Originally posted by C-3POTheClever
In A New Hope, it's clear that Luke doesn't unederstand R2D2 when R2 speaks, but et in TESB & ROTJ, he seems to understand what R2's saying. He R2 will beep & Luke will respond, even asnwering a few questions. How come? Hoiw come he can't understand him in ANH, but he can in TESB & ROTJ?

Yes, Luke doesn't understand R2. He uses a translator in his X-Wing.

On ESB he doesn't really talk WITH R2, more TO him, like people talk to their pets. He says stuff like "If you're saying coming here was a bad idea, I'm beginning to agree with you" that is not understanding r2's beeps. It's going back to R2 questions in the X-Wing about why they are going there.

And then there are the little human characteristics they give R2: he gets annoyed, he is headstrong etc. All things that are not really droidlike, but these are characteristics the film makers give them so we can relate to him a little. Like film makers so often do with animals. You can hear by certain sound if R2 is relaxing, or whether he is annoyed (like the squeak he gives when his throws up all that mud) or when he's feeling miserable (like in the rain). You don't need a translator to understand how the droid 'feels'.