What does "Redundancy" mean?

I know I said I would be leaving SW to focus on my college life but this is the only place I can really get help to understand certain stuff because my family is kinda in turmoil... Well, one quarter of my family as my cousin's workplace became redundant and he's lost his job because of it.

I wanna lend my support but I don't really understand it myself, please can anyone elaborate it for me, thanks?