From the recently released statement (taken slightly out of order):
Sex is an important biological variable that must be considered in the design and analysis of human and animal research. The terms sex and gender should not be used interchangeably. Sex is dichotomous, with sex determination in the fertilized zygote stemming from unequal expression of sex chromosomal genes. By contrast, gender includes perception of the individual as male, female, or other, both by the individual and by society; both humans and animals have sex, but only humans have gender. Both sexes produce estrogens, androgens, and progestins; there are no male- or female-specific sex hormones, per se, although these steroids are present in substantially different levels in males and females.
Much of the American public is surprisingly prudish about the word sex; it has now become commonplace to use the seemingly more genteel term gender when one really means sex. In Moritz v Commissioner of Internal Revenue (469 F. 2d 466 [1972]), Ruth Bader Ginsburg (subsequently, The Honorable Ruth Bader Ginsburg) argued against discrimination “on the basis of sex” not “on the basis of gender,” thus clearly, knowledgeably, and presciently understanding that “sex” does not equal “gender.” In a decision 48 years later (Bostock v Clayton County, 590 US, decided June 15, 2020), the United States Supreme Court separately ruled against discrimination on the basis of gender. Gender is often misused as a synonym for sex—for example, when filling out forms for various activities, we are routinely asked to check a box labeled “gender,” but the only available options are boxes labeled “M” and “F.” But sex is not the same thing as gender and using these terms as equivalents obfuscates differences that are real and important in society in general and biomedical research in particular.
Sex is a biological concept. Asexual reproduction (cloning) is routine in microorganisms and some plants, but most vertebrates and all mammals have 2 distinct sexes. Even single-cell organisms have “mating types” to facilitate sexual reproduction. Only cells belonging to different mating types can fuse together to reproduce sexually (2, 3). Sexual reproduction allows for exchange of genetic information and promotes genetic diversity. The classical biological definition of the 2 sexes is that females have ovaries and make larger female gametes (eggs), whereas males have testes and make smaller male gametes (sperm); the 2 gametes fertilize to form the zygote, which has the potential to become a new individual. The advantage of this simple definition is first that it can be applied universally to any species of sexually reproducing organism. Second, it is a bedrock concept of evolution, because selection of traits may differ in the 2 sexes. Thirdly, the definition can be extended to the ovaries and testes, and in this way the categories—female and male—can be applied also to individuals who have gonads but do not make gametes.
It does onto confirm that:
Gender identity is a psychological concept that refers to an individual’s self-perception; while associations between gender identity, neuroanatomic, genetic, and hormone levels exist, a clear causative biological underpinning of gender identity remains to be demonstrated.
I have only skimmed but those are two very important points. Later on there is a rather large inconsistency as it mentions 'sex assigned at birth' 
and I haven't got time to finish the rest. I thought it was a positive step though.
There is lots of extremely interesting information about sex and sex hormones etc and how it all works so I'll read through it in detail when I have time.
academic.oup.com/edrv/advance-article/doi/10.1210/endrev/bnaa034/6159361#.YG386Eqj1v4.twitter