Positive whole number exponents represent repeated multiplication of the base.
For example, 2^3 means 2*2*2. We have 3 copies of the base 2 multiplied
Another example: 2^4 = 2*2*2*2 showing four copies of '2' multiplied
When multiplying 2^3 with 2^4, we have 3+4 = 7 copies of 2 multiplied overall. Notice I added the exponents. So 2^3*2^4 = 2^(3+4) = 2^7
The general rule is that a^b*a^c = a^(b+c)