In this scene of Star Wars: The Force Awakens
we can see that Rey is freeing BB-8 which was captured by a Teedo. That Teedo was a scavenger and he captured a droid which could make him wealthy.
Why would he let Rey free BB-8? What did Rey say to him in the alien language (since it's not captioned in the film)?
She didn't tell him anything to convince him. She simply intimidated him, and he did not do anything while she released the droid.
But earlier, she told him to halt what he was doing:
At least until she understood the particulars of the confrontation she was witnessing, it was only right to call it to a momentary halt.
“Tal’ama parqual!”
Motion ceased as both the Teedo and BB-8 stopped wrestling and turned to peer up at her.
“Parqual! Zatana tappan-aboo!” Making an effort to simultaneously control both its heavy-headed mount and its captive, the Teedo yelled back through the mouthpiece of the goggle-eyed helmet that covered its reptilian cranium. Its attitude was decidedly unconciliatory, even threatening. Meanwhile the hovering head of the imprisoned droid swiveled rapidly back and forth, trying to watch both Teedo and human simultaneously.
Rey immediately took offense, not only at the Teedo’s tone, but at its speech, which far exceeded the bounds of common courtesy that existed between fellow desert-dwellers and made difficult coexistence possible. The luggabeast rider knew better, and its intemperate words were enough to decide her on a course of action. Descending the far side of the dune, she drew her knife and began hacking at the netting.
“Namago!” she growled. “Ta bana contoqual!”
Observing that it was on the verge of losing its prize, the Teedo unleashed a stream of indigenous invective. None of it had the slightest effect on Rey, who continued cutting away at the mesh until the native promulgated a slur that would have been vile in any language. Pausing in her work, she turned to face the tightly clothed creature, gesturing with her knife and fairly spitting a reply.
“Noma. Ano tamata, zatana.”
Long and drawn out, the Teedo’s response to this would have been unprintable on any of a hundred civilized worlds. Turning the metal-enclosed head of its mount, the unpleasant scavenger departed in the opposite direction. As soon as the native was a safe distance away, BB-8 rolled clear of the netting and began beeping loudly and challengingly in its direction.
“Shhh,” Rey hastened to quiet the droid. “Don’t tempt it. Enough insults can override anyone’s common sense, even a Teedo’s.” BB-8 instantly went silent. Together, the two of them tracked the luggabeast until it and its rider had vanished from view.
An electronic query drew her attention. Rey knelt down beside the questioning droid.
“He’s just a Teedo. A local. Not so unlike me, really.” Her expression twisted. “Except this one was particularly impolite. Wanted you for parts.”
Since we don't have a translation, we can only guess at the exact meaning, but one can PROBABLY guess it was something like "this isn't salvage, leave it alone".
No exact translation is given; on-screen there are no subtitles, and in the novelization the foreign language is transcribed directly.
However, the gist of what she is saying can be inferred from what she tells BB-8 after the rescue, and is backed up by her thoughts in the novelization. Basically, she considered what the Teedo was doing rude, and probably not completely legal. All she sees is a struggle between the Teedo and a droid, and her assumption (based on experience) is that the droid doesn't belong to the Teedo and it's trying to "abduct" it. So, she intervenes.
From there, the Teedo is apparently quite rude to her, and she decides to cut BB-8 loose just to spite him. What she and the Teedo are yelling at each other seems to be mostly just strings of angry insults. The Teedo is obviously intimidated by her, and doesn't consider BB-8 worth picking a fight over, so he just lets her take the droid.
Another guess: In Teedo's species/culture it may be that the one with the best/strongest insults wins, thus everything doesn't have to be decided by fighting and killing. And that's why Teedo didn't fight for the droid, which could make him quite rich. In a way, he followed his own species sense of honor. A species that only fights and kills to solve problems inevitably dooms itself to physically tough, unintelligent beings being the majority (with rare exceptions). History is evidence enough of that.
She isn't saying anything of meaning. This was an easter egg left by JJ. It's an anagram for "I am a Palpatine" and it was forced in as her first words to be a hidden "rhyme" with her final phrase "Rey Skywalker" if JJ were to have his ending (which he did) so she is naming herself in both the open and close but in secret since she could have easily ended up "Rey Salana".
It is important that it include the punctuation in the script as the "!" is and "i" the "u" is upside down as an "n" and the leftover "r" is to indicate "Rey." Kinda like some "I am Lord Voldemort" stuff in the Harry Potter series. This is why they chose to use an unestablished alien dialect.
