"Master", like a stereotypical maid calling her employer. Kept as is here to distinguish from Bourbon's "Master" (in English).

I'm done with my set of sit-ups!

So what sort of training are we going for today?

That's just inappropriate in so many ways! Other than the maid-master implication it can also have slave-master, BDSM sub-dom, wife/husband connotations, among others...