The Bible does not teach Purgatory nor praying for the dead. Ecclesiastes 9:5-6 indicates that once a person passes on from this life, “they have no more share in all that is done under the sun.” If we pray for the dead, the effort is fruitless because they are already in their permanent destiny. Luke 16:19-31 emphasizes this reality by making it clear that there are only two places people will end up when they die: heaven, or hell. Hebrews 9:27 shows that judgment follows death, so prayers for the dead are pointless. That eliminates all speculation of Purgatory existing in the afterlife. Scripture teaches that it is normal to still feel attached to those we have lost and grieve them deeply (John 11:35). During such times, we can turn to the family of God in our local church for support (Galatians 6:2). We can also run to Jesus Himself because He wants to carry our burden of grief with us (Matthew 11:28-30). The Bible also shows that believers have nothing to fear because we know from John 10:28-29 that we cannot be separated from our Heavenly Father—our destiny is forever with Him. Instead of partaking in practices that interact with the dead unbiblically, our time is better spent spreading the love of Jesus Christ to those who still live (Romans 12:9-10).
All Souls' Day is a Medieval-era church feast day meant to commemorate the dead. In Catholic and liturgical Protestant churches, certain saints are given specific feast days. All Saints' Day is for all the saints, whereas All Souls' Day is for every believer. The Orthodox Church traces the first All Souls' Day to 893, when Emperor Leo VI was denied his request to dedicate a church to the memory of his late wife, and dedicated it to all Christian souls instead. Originally, All Souls' Day was held around Easter time. The Orthodox Church celebrates it several times throughout the year, including four times around Lent. Roman Catholics and liturgical Protestants celebrate All Souls' Day on November 2, unless it falls on a Sunday, in which case it's moved to November 3.
Unfortunately, the Roman Catholic Church and some Protestants use the day to pray and do other indulgences to help loved ones supposedly escape Purgatory and continue on to heaven—-a highly unbiblical teaching. On the other hand, some Protestant countries use All Souls' Day to simply clean up grave sites, which is fine. While it is good to remember deceased friends and family members and is kind to neaten cemeteries, it is futile and (anti-biblical) to pray for the dead. As difficult as it may be to accept, the fates of those who have passed on are already sealed (Hebrews 9;27). It's best for Christians to avoid All Souls' Day activities that do not line up with the truth of God’s Word.