In the video, a man is seen writing on a whiteboard with a red marker. He starts by writing a triangle and then proceeds to write numbers next to it. He continues to write more numbers and equations on the board, and at one point, he writes the number 3632. The man seems to be explaining something, possibly related to the numbers he is writing. The whiteboard is the main focus of the video, and the man's actions are the main activity. The video does not provide any additional context or information about the man or the purpose of his writing.