To the Baha'is, the days that are named "Ayyam-i-Ha" are the "Intercalary Days".
These days occur between the 18th and 19th months of the Baha'i Calendar (26th February to 1st March inclusive), and end one day before the Baha'i fast begins. These days are spent in preparation for the fast. They are focused on actions of hospitality, charity, caring for the poor and sick, giving presents, and so on.
The Intercalary Days are also known as the Ha-days because they are associated with the letter "Ha." The numerical value of this Arabic letter is five, which corresponds to the number of intercalary days in a leap year. The letter "Ha" has several spiritual meanings in the Holy Writings of the Baha'i, one of which is as a symbol of the Essence of God.