Peter Holland, Martin Marincin, and Frank Corrado have all elected to go to arbitration. Arbitration hearings will happen from July 20th to August 4th.
Arbitration rules are pretty straight forward: the two parties participate in a hearing in front of an arbitrator. The arbitrator can award one- or two-year contracts--since this is player elected arbitration, the team chooses the term and can also walk away if the player is given more than $3.5M per year. None of these players are going get awarded anywhere near that much money, though.
The players and the team can negotiate and agree to a contract at any point between now and right before the arbitrator comes back with a number, which is what usually happens.