Let's first look at what you are printing:
((10**i -1)//9)*((10**i -1)//9)
#that is the math task, from which you are printing the result
You asked what
This is the multiplication operator...
Let's look at the other things, so you get a better understanding of what is going on
result = 10**i - 1
Here you are doing 10 to the power of i and then minus one.
** operator means to the power of...
2**4 means 2^4 or two to the power of four.
Then you are dividing the result of that task with 9
You are using
// which is the floor division. This will cut of the decimal place.
The right side after the
* is just the same as the first one.
You multiply them with the
result = (10**i -1)//9
print( result * result ) #Multiplication
I hope that this helped you.