Is 132 a good IQ score for a 15 year old boy and why?
It depends on what kind of test you took. If it was a genuine IQ test with a mean of 100 and a standard deviation of 15 such as the Wechsler Intelligence Scale for Children or Wechsler Adult Intelligence Scale, administered and scored by a trained psychologist, then yes, that is an excellent score.
The general public is strictly prohibited from having access to IQ tests such as the WISC, WAIS, or the Stanford-Binet. And so if you took this test online or obtained it from anywhere other than a psychologist, then it is guaranteed to be fake and your score is meaningless.
Online so-called IQ tests generally have built in positive biases to give the test-taker a very high genius-level score, making them feel good about themselves, and encouraging them to part with their email address or credit card details in return for a "full analysis" that is completely made up.