Person A: where do u see 5y5y = where is XYZ financial instrument trading? (in this case, a 5y5y forward swap, I'm guessing)
B: size? = how much do you want to buy or sell?
A: 20k = $20,000
B: 2.4456/2.4511 = bid/offer = price/rate that A can sell/buy at
A: tx