One study using MCF-7 breast cancer cells (a cell line responsive to estrogen) noted that Maca at -100ug/mL was able to induce proliferation and induced notable estrogenicity at 100-200ug/mL concentration, but was less potent than physiological concentrations of estrogen;  the potency was comparable to that of Silymarin from Milk Thistle .  Estrogenic effects have been seen in vivo when ovariectomized rats were given /kg ethanolic extract of Maca (equivalent to /kg root extract), where the measured uterine weight after 28 weeks was % of ovariectomized control but % that of non-menopausal control.  Another study using a lower dose of three variants of Maca for 4 weeks failed to establish estrogenic effects,  and estrogenic effects have also failed to be observed in other in vitro assays. 
Testosterone is a hormone that is produced in large amounts by males (and a little bit in females), in the testes and adrenal glands. High testosterone levels are associated with sexual performance, reproductive function, muscle mass, hair growth, aggressive, competitive behaviors, and other such manly things. Testosterone levels tend to peak at the age of 40, and slowly decline from there. Luckily, there are many things you can do to increase testosterone, so if you feel like your T levels could use a boost, you've come to the right place.