This could seem to be a stupid question to natives but I'll just try. Recently I found out that the most difficult kind of sentence in English are none other than the simple declarative sentences. (I have no clue that which grammar subject I should look up.)
I was wondering how come just stating the current state can have so many different meanings, especially when the subject is You or We. Such as...
(A) We are running away.
(B) Let's run away.
When someone says (A), how could natives take that as (B) in some contexts? Where does the "Let's" come from? When you say like "It's running away", you do not expect that that phrase would mean "Let it run away". Do you? I'm not a native, so I don't have much confidence in this. But anyway, how do you tell which is (A) or (B) just by hearing(or reading) the (A)?
Similar examples are so many.
In a video game, Overwatch, there's this character who yells "Nerf this!" which means "Just you try to nerf this". How do you tell this from "Nerf this(= Please do me a favor and be sure to nerf this)"?
In a TV show, Modern Family, a mom says to her daughter that "You're not wearing that outfit" meaning "I won't have you wear that outfit". How do you tell this from "You're not wearing that outfit(= I know what you're wearing now and it seems you didn't try that one though)"?