Today we'll wind up that deal with the bank.
'Wind up' is used in two rather different ways:
1. To input energy as in to wind up a clock spring so it will run for several hours. In the same way a baseball pitcher will wind up to throw the ball to the batter.
2. To conclude, to finish, to end at a (perhaps random) place after a series of events. "I don't want to wind up like that guy- in prison." This is also used in the past tense to talk about how things turned out. "We talked about several options, but wound up going to the movies."
I would take your example sentence to understand that you have been negotiating some transaction with the bank. Today you will conclude your negotiations and reach some final agreement.
Student or Learner