I can't understand ** ??

Answer 1

If x = 2 and y = 3, then x**y is 2*2*2. It's just that 'x' is multiplied by itself for 'y' times.
For another example, 3**4 is 3*3*3*3.

x**y is called ' x raised to y '.
2**3 - 2 raised to 3
3**4 - 3 raised to 4.. and so on.

I hope this clears your doubt.

Answer 2

a ** b is equal to a * a * ... * a * a, b times

Answer 3

Am.'s answer is correct as far as it goes, but incomplete. You can have arbitrary complex (or in our case rational) numbers as exponents, not just positive integers.
You can find an easy explanation here. Especially look at sections integer exponents and rational exponents:
https://en.m.wikipedia.org/wiki/Exponentiation

Answer 4

if 2**3 means 2qube it means 2 will be multiplied by itself 3 times which is 8

Answer 5

google exponentation. You will get better than what I can explain without trying to put on a seminar.