
If you do not have basic reading comprehension capabilities, this is not the manhwa for you.

BLESS THIS COMMENT. So many people comment stupid shit on this page lately.

That person wasn't trying to make you feel shitty for not being able to remember Korean names. You said
"I don't understand nothing
Who is the person in the wallet?
And who the heck is the kid Lying in the bed?"
implying you haven't been following along with the basic storyline. They mentioned the person in the wallet just once. In one chapter in which they did not disclose the name of the person in the photo. Literally no one knows except Haribo. So it was rather pointless of you to ask something like that.
And the person lying in the bed is clearly the real Min Siwoon. In the second chapter, it literally shows Taemin surprised that his childhood name is in his new life -- but with a different name. He wonders why he goes by a new name often enough. And then Jiwook makes it clear that "Siwoon" (aka Woojin) doesn't look like his mother. Several chapters lead up to the big reveal that Woojin is not the real Siwoon. THAT is why the commenter commented what they did.
I totally understand that commenter's frustration. SO many people barely bother to keep up with character names and plot points? If you had just scrolled down a few pages on the comments, you will see more than 30 comments answering other questions similar to yours.

They never once said anything about OP not being able to remember Korean names. Lol.
P.S. Maychan, I can't take anything you say seriously after you have continuously excused Jiwook's actions and played them down because you think Joohoon is worse. Let's not forget when you also said that Jiwook "loved his brother the most". Haha. You clearly don't have a good perception of reality.

You speak about chapter 50 because we don't know yet who is the person Joohoon keeps or kept in his wallet.

I know this I just wanted an answer I asked because I thought maybe I haven't seen something my native language is spanish and sometimes Is really hard to not to miss something I read this for so very long sometimes I stray away and forget important parts of the plot thank you for explaining but people don't have to be so rude

Again, not what positive was talking about. If you strayed away from the story, all you need to do is go back to the parts you think you might have missed. And there is no reading required in order to understand them. Plus they also mentioned another thing you obviously missed. Something about answering this very same question for thirty or more comments already. If you read their answers I'm sure you'll get the one you're looking for, too, right...?
I don't understand nothing
Who is the person in the wallet?
And who the heck is the kid Lying in the bed?
And please i'm not good with names so someone can like put the names because i keep remembering as blue haired guy and the guy who died and came back to life in another person body