What is this diagram and what does this key mean

Numbers behind the | are in bold

0| 5 9 8 3 4 1
1| 6 3 1 0 3
2| 8 2
3|1 1 6 9 3
4|6 9 9 4 7 0
5| 5 7 7 6
6|0 2 8 4 8 0 3 5
7| 6 8 0 1 5 4
8| 6 6 9 2 8 5 7
9|6 7 8 0 0

Also, what does this mean

Key: 1 | 3 means 13? What does this mean!?!

This is a set of numbers. The numbers on the left represent the tens digit. The numbers on the right represents the ones digits. For example, 5| 5 7 7 6 are the numbers 55, 57, 57, 56.

if 1I 3 means 13, then

these are all 2 digit numbers with numbers behind I being 1st no. followed by the number on the right.

for example,

last no means 96,97,98,90,90