Pesach begins with a special meal, the Seder. In the past 250 years or so, the custom has grown to conclude it with another special meal on the final afternoon of Pesach, known as Moshiach Seudah, or the Messiah's meal.
The Moshiach Seudah was instituted by the Ba'al Shem Tov (1698-1760) the founder of Chasidism, and is today practised mostly by Chasid, especially from Chabad (Lubavitch). The custom is to eat matzah and drink four cups of wine at the meal.
The idea of the Moshaich seudah is to look forward to the complete messianic redemption in the future. As the Tzemach Tzedek, the third Lubavitcher Rebbe put it, "The last day of Pesach is the conclusion of that which began on the first night of Pesach. The first night of Pesach is our festival commemorating our redemption from Egypt .... The last day of Pesach is our festival commemorating the final redemption."