0/0 is an "indeterminate" expression.
The reason that 6/2 is 3 is because 2 x 3 = 6. (In other words, it "checks.")
When you divide 0/0, you might think that the answer is 0, because it checks: 0 x 0 = 0.
However, you might think that the answer is 6, because 6 also checks: 0 x 6 = 0.
Try -4: 0/0 = -4 ---> 0 x -4 = 0, It also works!
In fact, every number works! That's why it's called "indeterminate"; there is no specific answer.
When you take calculus, you find that the problem that led to that "solution" determines the value of 0/0.
Sometimes, it is a number, like 6, or -4, or even 0.
Sometimes, it isn't a number, for instance, ∞.
