The term is simple once you know the structure behind it.
A parashah is a Torah section
Britannica explains in its article on sidra that each weekly Torah portion is divided into seven smaller sections and that each of those sections is called a parashah.
That means the word can refer broadly to a Torah section, but in synagogue life it often names one of the divisions used in public reading.
The term matters because public reading is structured
The weekly Torah reading is not improvised. It is divided into portions and sub-portions so the community can hear the text in ordered segments.
Why it still matters
Parashah still matters because Torah reading in Judaism is not just about content. It is about recurring communal structure. The division of the text shapes how Jews encounter it week after week.
The shortest accurate answer
A parashah is a section of the Torah, especially one of the divisions used in public synagogue reading as part of the weekly cycle.