Virility refers to all the physical characteristics of adult men but also all the qualities (courage, strength, honor) that are culturally attributed to men.
We also talk about virility to talk about men’s sexual behaviors and ability to procreate (see fertility).
The vision of grown men has evolved through ages : during Antiquity, the manly man is the warrior, during the Middle Ages he’s the knight or the courtier, during the 20th century he’s the soldier who goes to war. The common point between these different periods is that virility is associated with fighting, braveness and strength (see strength).
On the contrary, femininity is associated with softness, weakness... When a man isn’t brave or strong, or enjoys “feminine” things, some people are gonna say that he acts like a woman.
Virility can lead to toxic masculinity : a man must be strong, he mustn't show his emotions and his weaknesses, otherwise he’s not a true man. We often find this mentality in little boys’ education : they can’t cry, they have to enjoy fighting. Just like a woman has to be feminine to be considered to be a real woman. All of this comes from the fact that we live in a patriarchal society that wants to put men and women in a box from which they can’t escape.
Also, too much virility can lead to bad tendencies like the inability to admit your mistakes, especially to a woman, to admit that you can be weak and have emotions, to brutality... according to people during Antiquity, these tendencies get the man closer to the beast.