Jumma means “Friday”.
Jumma, also transcribed as Jummah, is the sixth day of the Islamic week. As the Islamic week starts on Sunday, this falls on Friday. Jumma is considered to the holiest day of the week, and Muslims are advised to not work on that day, rest and partake in prayers. In fact, in predominantly Islamic countries, the weekly off is on Friday (Jumma) as opposed to the western traditional Sunday.
The literal meaning of Jumma is congregation. Hence, on Friday, Muslims must visit the mosque to offer their prayers. It is said that on Friday, the angle sit at every door of the Masjid, and write down the names of everyone who enters. On Fridays, the Imam also offers Khutbah, which is essentially a sermon given to people.
On Jumma, a Muslim must bathe, wear fresh and clean clothes, and go to the mosque for prayers as soon as called. It is also forbidden to fast on a Jumma.