Yeah I was trying to figure that out because there was a conflict going on when translated that they mentioned a "weapon" and it caused chaos worldwide and every nation was ready to go to full out war. What about that scene with her talking to the Chinese general in Chinese and it changed the course everything, did that scene have something to do with the weapon that she received by fully understanding or at least able to know a lot of the Heptapod language and it changed the outcome of how things that were bad are going to be good? What about the part where she said that she knows that their daughter will have a disease, does Jeremy Renner's character, Ian Donnelly, know yet near the end where he finally admits saying that all this time he learned a lot importantly was her or something along those lines, does he know that they're going to get married and have a daughter and that their daughter will pass away from a disease?
This movie is really one of those complicated movies that allows the audience to understand which is what I really liked about it. I hope we get more movies like this.

Her "weapon" was a full understand of the heptapod language. One of the ideas of the film is that the way someone uses languages affects how their brain perceives things. The heptapod language relies on circular shapes and knowing how each sentence will end. Once Louise understood this fundamental rule of the language, she was able to perceive time in the same way that the heptapods do: not as a line but as a circle. That's a radical shift in awareness that could mean huge changes in how humanity develops. This "weapon" is what allows Louise to decode their final message and bring things together.

Learning their language allowed her to perceive time non-linearly entirely, not ONLY "see the future". So that suggests that it doesn't matter that we don't see her learn the language until "later", she's already experiencing time in a nonlinear way because she learned it at
all
, ever. The visions at the beginning of the film are as nonlinear as everything else in the movie. When we see the visions, she's already met the aliens, and when we don't see them she hasn't yet/is in the process of it. Her entire experience of time isn't linear (Hopefully you get what I'm trying to say lol.)

So those random visions, especially the ones of her daughters are in the future and not a flashback that didn't happen yet? My question is, how how was she able to have those visions already prior to eeeting the Aliens? Was she already able to see the future before too or I think those random scenes were for just the audience to see and doesn't have anything yet for her to know what's going to happen?

She was given the ability to see into the future. No one else. Jeremy Renner leaves her after she tells him that she knew the daughter they would have would die young of cancer. He thinks she made the wrong decision by staying the course.