The characters literally combine to mean “his mother's,” which is the core of a much more explicit insult. However, just like “son of a bitch” in English, the phrase has evolved into a general-purpose curse word where the literal meaning is rarely the focus.
In Chinese culture, which is deeply influenced by Confucian values, family and filial piety (孝, xiào) are paramount. Insulting someone's parents, especially their mother, is considered one of the most severe personal attacks imaginable. This is why “他妈的” and its more explicit variations are historically so potent and offensive. The closest Western comparison is the F-word. Both “fuck” and “他妈的” started as extremely taboo phrases but have gradually become ubiquitous in informal speech as general expletives and intensifiers. However, a key difference remains: directly insulting someone's actual mother with “他妈的” in a heated argument in China carries a heavier cultural weight and is more likely to provoke a physical confrontation than a similar insult in many Western contexts. It cuts deeper because it attacks the root of a person's identity and honor – their family lineage.
“他妈的” is incredibly flexible and its meaning is defined by context.