For example If a boss needs to hire a good secretary for one of his employees; and assign him the task of finding one and then tells him "Don't let your hormones decide for you" is pretty clear what he means; that sexual attraction and gender should be irrelevant in the selection proccess and he should focus in practical skills a secretary should have. And there is nothing sexist about that; because sexism is discrimination based on gender and this is an enforcement for the lack of that kind of discrimination.
Also, why does it have to be a secretary? Are they 100% female now? If he was looking for an engineer, would he need to be told not to let his hormones decide?
The majority of secretaries are female (not all); and is no secret that sometimes people hire based on looks instead of actual skills.