Lent is an important part of the Christian calendar that begins on Ash Wednesday and continues for the next 40 days (about six weeks) before Easter Day. The idea of Lent is to prepare oneself for the time of death, burial and resurrection of Jesus by making a form of sacrifice, usually by eating less food (fasting), or stopping eating some food, such as meat, altogether. The main events at the end of Lent are Maundy Thursday (day of the Last Supper), Good Friday (day of the Crucifixion) and Easter Sunday (day of the Resurrection).
Many churches do not have flowers on their altars at this time, and veils are put over crucifixes.
Shrove Tuesday is also called pancake day. It is the day when you get rid of [Old English 'shrive'] items that are not allowed during Lent, and so make them into a feast of foods such as pancakes.
Ash Wednesday is a Christian holy day of prayer, fasting, and repentance. It follows Shrove Tuesday (Pancake Day) and is the first day of Lent, six weeks before Easter.
The name comes from the placing of repentance ashes on foreheads while saying the words "Repent, and believe in the Gospel" or "Remember that you are dust, and to dust you shall return" [where 'ashes' mean 'dust'].
The video is one of many we have about the time leading up to the Crucifixion.