what does"test-prep giants"mean?
Vivian Kerr has been teaching and tutoring in the Los Angeles area since 2005. She graduated from the University of Southern California, studied abroad in London, and has worked for several test-prep giants tutoring, writing content, and blogging about all things SAT, ACT, GRE, and GMAT.are "test-prep giants tutoring", "writing content" and "blogging " all institutions？ or just subjects? then, what does "test-prep giants tutoring"& "writing content"mean?

Question

what does"test-prep giants"mean?
Vivian Kerr has been teaching and tutoring in the Los Angeles area since 2005. She graduated from the University of Southern California, studied abroad in London, and has worked for several test-prep giants  tutoring, writing content, and blogging about all things SAT, ACT, GRE, and GMAT.are "test-prep giants tutoring", "writing content" and "blogging " all institutions？ or just subjects? then, what does "test-prep giants tutoring"& "writing content"mean?

Answer

I think "test-prep giants" refers to the most popular companies that produce materials for those taking standardized tests, such as the ACT, SAT, GRE, GMAT, and so on.

In this context, it means the person worked for these companies, and her work included tutoring, writing content (for example, perhaps something on their website), and blogging.