When things come in sequence, they come in a specific order. It could be a chronological sequence, a sequence following a pattern (red-blue-brown, red-blue-brown), or a cause-and-effect sequence.
Sequence can also be a verb. When you sequence something, you put it in order. The prom committee had the task of sequencing dance music––even if playing "Celebrate" as the final dance and not the first felt out of sequence to the DJ, it was their call.