'폼' ? '날/나를'?
[...]폼 한 번 잡아봤어요
I used to know that 폼 means 'form' for here I think that meaning has no sense ... for the context, before that sentence the person said: ''I bought a new glasses''

[...] 메이크업 한 날보다 안 한날이 훨씬 많아지니까 [...]

And about the structure of this one there are two '날' (날보다 and 날이), 날 means 'day' but I also read that can be the short form of '나를' so now I've a mental breakdown to know which meaning is correct ...

Thanks in advance !

Question

'폼' ? '날/나를'?
[...]폼 한 번 잡아봤어요 
I used to know that 폼 means 'form' for here I think that meaning has no sense ... for the context, before that sentence the person said: ''I bought a new glasses''

[...] 메이크업  한 날보다 안 한날이 훨씬 많아지니까 [...]

And about the structure of this one there are two '날' (날보다 and 날이), 날 means 'day' but I also read that can be the short form of '나를' so now I've a mental breakdown to know which meaning is correct ...

Thanks in advance !

Answer

폼 means literally form - visible shape, style, design and a particular way etc. .

But it has other meanings

- an ironic or humorous behavior 
 - describe someone starts something or get prepared.
 
(폼을 잡다: put on airs or pompous air)

Ex)  새 안경을 사서, 폼 한 번 잡아봤어요.

I bought new glasses, so I put on airs.

아마 Kenny는 지금 낮잠 자려 폼 잡고 있을걸.

Maybe Kenny get preparing a nap now.

날 can be used in expressing something special days,  as it is added at word's back.

Ex)
어린이날 ( Children's day )
한글날 ( Hangul Proclamation Day )

오늘은 좋은 날이 아니다. 
(Today is not good day.)

날 also is a shortcut for 나를.

In your sentence , it is used  as the meaning of "Day" .