Laylat al-Baraat or Shab-e-Barat 2021 will be observed on 28th of March,namely August 15th 1442AH.it is regarded as a night when the fortunes of individuals for the coming year are decided and when Allah may forgive sinners.
"Baraat" means "innocent"in Arabic. According to legend, on the night of August 15th in islamic calender, Muhammad went to in Medina alone to pray. Afterwards, he told the disciples that this night Allah descended closest to the world, and told that all Muslims who sincerely repent of sins, pray for forgiveness on that night can get permission.
We can find some description of it in the Hadith:
Doubtlessly, Allah surrounds everything on the fifteenth night of Shaban with his mercy. He forgives all of His creatures except mushriks (polytheists) and those whose hearts are full of hatred or enmity of others. Allah, the Exalted, forgives all Muslims on that night except soothsayers, magicians, people who are full of hatred, alcoholics, people who harm their parents and those who insist on committing fornication. Al-Targhib wa al-Tarhib, 2:118
In the Arab world, this festival is celebrated by Arabs with Sufi heritage and Shiites. The Salafi Arabs do not celebrate it.And different countries have different tranditions.Generally speaking,you can spend the night by doing good deeds, such as making duas for yourself and all Muslims in the world, reciting the Quran and any other actions to attract the attention and blessings of Allah.