Golden Week is a special week for the people of China and Japan. During this week they have 4 special events which are celebrated on April 29 and from May 3 to May 5 every year. It's just like holidays on Christmas.
Golden week is also referred as "GW".
Why Shonen Jump is on Break?
As the majority of the people don't like to work during public holidays so Manga writers are same they don't publish raw chapters during this week instead they spend vacations with family and free themselves from the burden of consecutive work. This is the reason why all Shonen manga authors Masashi Kishimoto (Naruto's Author), Eiichiro Oda (One Piece Author), Tite Kubo Bleach author and many other takes break from their work.
The sole purpose of this post was to inform people who are not the residents of Japan and China about Golden week, as majority of the anime and manga fans gets angry on mangkas for not releasing new chapters without any good reasons. Golden Week is celebrated once a year in Japan and such other countries.