The Haft Sīn Spread is like the Christmas Tree for Nowruz. Nowruz is the New Year Festival in West and Central Asia! It begins at the moment of the Vernal Equinox around 20-21st of March every year (in the Northern Hemisphere) and lasts for 13 days!
The 7 staples of Haft Sīn symbolize re-birth, good health, and Spring!
One day before the Vernal Equinox (aka Spring or March Equinox) which is the precise moment of the New Year, we lay out the Haft Sīn spread on the floor or on a table. The Haft Sīn spread consists of 7 edible, vegetal, or symbolic items that start with the letter "S" (sīn) in Persian and we decorate it with painted eggs, candles, mirror, a holy book or book of poetry!
For more detailed information about Nowruz & Haft Sīn, see my "Nowruz is Science" Infographic (in this same forum).