What the sign label means
The ninth 30° segment. Whole-sign houses count from the rising sign, so its house number varies by birth time and place.
A body is listed in Sagittarius when its normalized sidereal longitude falls from 240°00′ up to—but not including—270°00′. The exact degree within the sign remains important, particularly near either edge.
Sign is not the same as house
The sign is a fixed part of the 360° circle. In a whole-sign chart, the house number depends on the ascendant: the rising sign is house one, and the following signs are numbered in order. Sagittarius can therefore be a different house in different birth charts.
Element and mode are traditional classification labels. They do not, on their own, establish a personality or predict an event.