With a Split Deal you create a new blockchain address which automatically splits the incoming funds between your account and the defined target account.
You have to name your deal. The name has to be unique accross the system.
The target address is the final recipient of the funds minus commission.
Incoming funds will be split between you and target address according to the commission rate.
A commission rate of 1.00 for example would been that the target address will receive 99% of the incoming funds.