Addition is the total value of one or more numbers combined.
The form for writing "add this number to this number" is "n1 + n2" where n1 is the first number and n2 is the second number.
The first and second numbers or the numbers that you are "adding" are called addends
You could also represent addition vertically like: 5 ← the first number
+ 3 ← the second number
---- ← a line to seperate the sum from the addends
8 ← the sum
Take the example above. How did we get 5 + 3 = 8? The initial way to understand is to use your hands.
First, close both your fists, and open up 5 fingers. Then, open up three more fingers. Count...how many fingers are opened right now?
As you get to be able to do it faster, you will be able to do it mentally.
Now, let's do something more complicated!
We could also do addition with 2 digit numbers, 3 digit numbers, and so on.
To learn how to do so, look at the video below.
Essentially, an example would be: 1