I was just thinking about this the other day. Interesting

I don't believe dogs or animals in general actually understand the language their owners speak rather they recognize the speech patterns and tone of voice linked with certain actions and fulfill the action that is matched, with that certain speech pattern and/or tone of voice.

I mean, would a dog that understands English words not understand Chinese words?

This is quite the conundrum....I have no idea how to respond...it's too tricky!

I have three dogs. THEY UNDERSTAND. I have to watch what I say, lest they get triggered by a word! Examples: out, treat, snack, food, what's that, etc.

No. They understand commands, not phrases(excluding the possibility a command may be a phrase) but I think dogs have their own form of communication. They have growls, whines, howls, and so on to not communicate through words, but rather emotions. It's sort of like body language or what some people may call it, the international language of the body(okay, I just made that up but you get what I'm saying); dogs, cats, birds, whatever creature, even humans have ways more than just speaking to communicate so no, an American dog should be able to communicate with a Chinese dog just fine from my train of thought. Now, to commands: a command is like learning a new language. As a code, only you and someone else know. I'll tell you my dog "spit it out" when I want her to drop her ball while someone else could say "drop it" to do the exact same thing but if we were to say the same command to another dog unless they have the same command using the same words, they won't understand so no, I do not believe dogs can understand us like we humans understand each other. That's just my thoughts though, I didn't do much scientific research or anything to back my theory up so please, correct me if I am wrong.

I have one maltipoo. earlier, I was making rice and khorisht, (an Armenian slew-like food) and my dog barked at me, then whimpered. I said, "What's wrong?" expecting nothing to happen, because I thought he doesn't understand me. then he gestured his head towards the pot of food, and gave me the puppy eyes. I was a little stunned. I said, "that's unhealthy for you, no." and he made a series of growls, whimpers, and barks. this lasted for 30 seconds, about. I think he was trying to give a speech about why he should be allowed to eat it...

so yes, dogs do understand what humans say, and they try to talk back.