what is ...말만 잘 할거라고 생각해? translated to English?
...말만 잘 할거라고 생각해?

I know each word individually but i can't seem to figure out the sentence structure in English to make it, make sense.
To give an idea of what's going on, if it helps, these were said beforehand...

Person A: 너무 기뻐서 가슴이 터져버릴 것 같으니까.
Person B: 말은 잘 하네
Person A: ...말만 잘 할거라고 생각해?

Also what does 스윽.. i keep seeing it in manhwa as a background sound/action word and i can't tell if it's something to do with touch, sliding,pulling, or other

Question

what is ...말만 잘 할거라고 생각해? translated to English?
...말만 잘 할거라고 생각해?

I know each word individually but i can't seem to figure out the sentence structure in English to make it, make sense.
To give an idea of what's going on, if it helps, these were said beforehand...

Person A: 너무 기뻐서 가슴이 터져버릴 것 같으니까.
Person B: 말은 잘 하네
Person A: ...말만 잘 할거라고 생각해?

Also what does 스윽.. i keep seeing it in manhwa as a background sound/action word and i can't tell if  it's something to do with touch, sliding,pulling, or other

Answer

말만 잘할거라고 생각해 can translate:  I'm not just bluffing 
and about 스윽, its kind of sound effect when you reach to grab something or you move slow or gently.

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