Often, when we think about APA style, we think about formatting guidelines: how to format a reference for a book or an article, how to write and format headings, what size paper margins should be used, and what belongs in the running header. The Publication Manual of the APA goes over these formatting details, but it also provides valuable guidelines on writing style. This includes how to reduce bias in written language.
If you have a copy of the Publication Manual of the APA in hand, you can read the section, "Reducing Bias in Language," p. 70-77, for a complete discussion of recommended use.
The APA Style blog has an insightful and concise discussion of these guidelines, titled "A Little Respect." You can read more here.
Another post addresses the adoption of the singular, non-gendered pronoun, "they," which you can read here.