What does this notation mean?

Hi, I'm working through a Linear Algebra textbook and I've run into a notation that I can't seem to find explained in the textbook. At least, I think it's a notation?

Basically, I was given two arrays like:

........2 0 3

A =..4 2 3

........5 3 2

........5 0 4

B = ..7 3 3

........2 3 1

(numbers are made up, if it matters I can dig up the actual numbers)

The first things I had to do with this was figure out 2A - 2B, this was all well and good.

The second thing I had to do was figure out . There is the issue, I'm not sure what this T is, I don't see any value assigned to T in the question and I can't find an explanation of what to do with T in the textbook.

Does anyone know what this means? Thanks!