TB can be used to refer to either decimal measurements (1TB = 1,000GB; 1GB = 1,000MB; 1MB = 1,000 KB; 1KB = 1,000B) or binary measurements (1TB = 1,024GB; 1GB = 1,024MB; 1MB = 1,024 KB; 1KB = 1,024B). TiB refers explicitly to the latter.
Either way, it means terabyte.
Tebibyte actually
Now that I think about it... wouldn't it be TeB or TaB? //confused
No. I'd have called it a TbB myself, but hey, I didn't invent it.