Things that come one after another in a particular order.
Sequencies are important for understanding how things happen.
Examples:
I like to watch the sequencies of the stars in the sky.
The sequencies of the days of the week help us know what day it is.
The sequencies of the alphabet are important for learning to read.
The sequencies of the colors in the rainbow are very pretty.
The sequencies of the numbers in the counting song help me learn to count.
The sequencies of the seasons changing make the world beautiful.