Hello @tuo88138,
Welcome to the JMP Community!
Standard JMP uses 2-level validation as a rule and JMP Pro has 3-level validation built in to the Analyze platform under Predictive Modeling. In Standard JMP, you can always hide and exclude your test set data when building your model and then bring it back in to see how it affects your model and/or how well the training and validation sets did in the modeling process.
You can also build your own validation columns manually in JMP Pro. Create a new column and go to Column Info and the Initialize Data > Missing/Empty drop down. Select Random and Random Indicator to break the data up into 2 or 3 level validation sets. To see how to build a validation column in JMP Pro check out the link below.
Creating a Validation Column (Holdout Sample) | JMP
HTH
Bill