That is not a symbol. It is a parchment scroll, on which a scribe has hand-written Deuteronomy 6:4-9 and 11:13-21, as commanded there. The scroll is rolled up and inserted into a case, which is attached to the doorpost which is on the right as one enters. This is done for every doorway in a Jewish home, except the bathroom.
It is a mezuzah.
The mezuzah is a small rectangular container which holds a parchment inscribed with the portion from Scriptures called the Shema: "Hear, O Israel..." (Deuteronomy 6:4-9 and 11:13-21) which reminds Jews that we are answerable to God, that we are to love Him and keep His commandments, and to be diligent to teach our children His ways. As we come into the home, we have this reminder before us (usually on the right-hand side as one enters). Etymologically, the word "mezuzot" means the doorposts, but the term has come to be used for the container with the parchment which is affixed to the doorpost.
A wreath.
The thing people used to hang others on was called a gallows.
Yes. It is their way of celebration
You hang Christmas stockings, with care.
People hang a bag of water from their front door to keep flies from coming into the home. The bag has a small hole in it and the flies get in but then can't get out.
The thing used to hang people is a noose.
To show pride in their country!
To hang a bi-fold door, start by installing the track at the top of the door frame. Then, attach the pivot brackets to the top and bottom of the door. Finally, hang the door onto the track and adjust the positioning as needed for smooth operation.
福 [fú]They usually hang it upside down so it can bring them luck.
Wreaths are traditionally hung on the door at Christmas time.
If you mean the word "wreath" as in the circular thing you hang on your door around Christmas, then obviously the silent letter is the "W"
on your door