pronounce can't and can

[ref1]

I just came to the US and I'm always confused when people say can't and can
I don't know which word are they saying.

Can't has the t sound at the end, but most American people don't say that t sound. So they just say like Can'
so it's the same thing as can - the opposite word

and the important thing is i don't know to pronounce those 2 words exactly and sometimes I don't understand what they say either.

[mxreader]

For ESL I suggest you say it like the English/British. This is for clarity and there is little chance that you will be misunderstood.

So say "can't" with an "a" as in "argue".

[BobK]

I just came to the US and I'm always confused when people say can't and can
I don't know which word are they saying.

Can't has the t sound at the end, but most American people don't say that t sound. So they just say like Can'
so it's the same thing as can - the opposite word

and the important thing is i don't know to pronounce those 2 words exactly and sometimes I don't understand what they say either.

Interesting observation. If you ask most Br Eng speakers - probably with the sole exception of people who have studied phonology - 'What's the difference between can and can't?' you'll get the answer 'One's got a t'. But what we really listen for to distinguish the two is the vowel sound. So follow mxreader's advice. Often, when a speaker of Am Eng says 'can't' I have to think twice about what I really heard (and whether one or the other makes more sense in the context - If an American seems to say 'Sorry, I can' I can guess [because of the 'Sorry'] that 'can't is the more likely of the two.

But on the last point you're wrong: there is an audible difference between [kæn] and [kænʖ], just as there is an audible difference in Br Eng between [kæn] and [ka:nʖ]. It's just that the difference, in Br Eng, doesn't depend on your hearing the [ʖ] - which is often an indistinct sound (but it's there, as a spectrograph would show).

b

[Barb_D]

Even native speakers have to stop someone to say "I'm sorry -- did you just say he can or he cannot?" from time to time. Context will often help, but not always. I agree that it can be very hard to hear the difference sometimes.

[SoothingDave]

You're not alone.