What's a schwa?

[ArtsyP!nk]

So I've been planning on doing an English voicebank, and while looking at the instructions of a reclist (Resolist if y'all wanted to know what reclist instructions I'm reading), I read that the "C" portion of the reclist is recorded with a schwa. I have no idea what that means. So what does this mean? Is it like a tone that tags on the end of a recording, or is it something different?

 

[ammamanagucci]

i hope this could help even tho its for american english but im sure it'll apply to british english

 

[ArtsyP!nk]

That lady is staring into my soul lol
After checking, it seems that the schwa is the same for british english. Thanks for showing me that video!
Hopefully this goes well ('cause I'm not british at all. I don't even have a cool accent. Missed my country's accent lol)!