Having a positive exponent means
having a positive number as a power for a value or a variable.For example:
Here, the variable
x has a positive exponent because it has a power of positive (+) 2
This expression has a positive exponent because the number
1 has a power of positive (+)1 and the number
2 has a power of positive (+)4

This is not a positive exponent because the variable
x has a power of negative (-)2
The positive exponent for

is

.

This expression doesn't have a positive exponent. Though number
1 in the numerator has a positive power (exponent), the number
2 in the denominator has a power of negative (-)4
The positive exponent for

would be

.
NOTE: The terms Power and Exponent have he same meanine i.e. They are the same !!!