Skip counting by 2s, 5s, and 10s models repeated addition and becomes the foundation for multiplication. Counting 2, 4, 6, 8 is equivalent to 2+2+2+2, which represents 4 groups of 2 or 4 × 2.
You know how to skip count by 2s: 2, 4, 6, 8, 10... Each step you take, you add 2. Now here is the important question: what are you actually doing when you skip count? You are adding the same number over and over again — that is called repeated addition. Saying "2, 4, 6, 8" is the same as saying "2 + 2 + 2 + 2." And "2 + 2 + 2 + 2" means you have four groups of 2. That is exactly what multiplication describes.
Think about it with a picture. Imagine 4 pairs of shoes in a hallway. You could count every shoe one by one: 1, 2, 3, 4, 5, 6, 7, 8. Or you could skip count by 2s because each pair has 2 shoes: 2, 4, 6, 8. You land on 8. That skip count is doing the same work as 4 × 2 = 8. Skip counting is multiplication in disguise — you just do not write the × sign yet.
The same idea works for 5s and 10s. Counting nickels — 5, 10, 15, 20 — is skip counting by 5s, and it means you have 4 nickels worth 5 cents each: 4 × 5 = 20. Counting by 10s — 10, 20, 30 — is 3 groups of 10: 3 × 10 = 30. The groups are your count of how many times you skip, and the skip size is the number you multiply by.
When you learn multiplication tables next year, skip counting will already be in your memory. The 5-times table is just the sequence 5, 10, 15, 20, 25... which you already know. The hard work of memorizing is largely done. Every time you skip count now, you are rehearsing future multiplication facts without even realizing it.