I would describe it a bit differently myself tbh.

When used as a Marxist it's a contrast with "idealism". An idealist (which isn't really a thing in itself) might think something like "social relations and historical events are driven by the ideas of the people in those societies, and the ideas of their leadership. We can learn a lot about society by focusing on the ideas of the past and present and developing new ones that will set us onto a better future".

Materialism is along the lines of "social relations and historical events are driven by the material conditions, and when we study these things, we are looking at a snapshot of an ongoing process which lies at the intersection of the material world and society. The ideas held by people are generally secondary to the material conditions in which they occur."

To bring this together, an example could be one's outlook on the U.S. American economy. Most liberals are idealists, and many believe something like "The United States is a wealthy and powerful country because it has a lot of economic and [negative] political freedom. If we compare it to other countries, many of them are constricted in their development because they don't have the same economic and political structure that we do, but if they did, they would prosper as well. They just need more [liberal] democracy."

A materialist would say something more like "The United States has a powerful economy because the Europeans brought over advanced tools that allowed them to exploit the mostly untouched land, as well as brutal social structures like slavery and supremacy that allowed them to exploit Indians and labor. The liberal ideas that developed were downstream of this, since it propped up the interests of the powerful and allowed them to continue exploiting, while [free] laborers were often able to find the better opportunity that they were looking for as they immigrated to the New World. The combination of exploitable land and exploitative ideology allowed for centuries of rapid economic growth.

The United States' economy also benefited greatly from WWII when they increased production without having to suffer losses to their productive capacity like other participants did. They were able to use this advantage to wield their newly powerful position into an exploitative economic relationship with many other countries for the benefit of them and their allies".

Last thing I'll add is that "material conditions" are exactly what they sound like: geography, weather, technology, the health and wellbeing of people, natural resources etc... since that sometimes gets obfuscated