Answer:
The pH scale basically determines how acidic or basic something is. The scale is 0 to 14, with 7 representing stability/neutrality. Take a look at this image, maybe you'll have a better understanding of it. Now a pH indicator, just imagine dipping a measure in a solution to determine whether its an acidic or basic solution, if it turns red if the solution is acidic, if it's basic then it will turn blue/violet. That's what a pH indicator is. Take a look at the second image & hopefully you understand it.
Explanation: