Let me explain it with an example.

Assume I have a flow to enter the information about  vehicles. I have a custom object Vehicle and a custom object Tyre.

My flow is loaded in a Visualforce page, which shows the information that I previously entered on the right side, the flow itself showing on the left side.

First screen, I enter the information about the Vehicle, no problem. Inputfields are assigned to variables, variables showing on the right side in my visualforce page.

Next, I would like to enter all the information for each tyre of the vehicle.

We don't know upfront how many tyres each vehicles has (moto, car, truck, etc..). So this needs to be defined dynamically (maybe via a dropdown on the previous screen about the vehicle itself).

I understood we can loop in the Flow, but the problem I have in this case is that when the first tyre is entered, I assign the information of the inputfields to variables and when the next tyre is entered, the information of the first tyre is lost, because it's assignment to the variables is overwritten by the second tyre.

Note that in my specific case, I only create the records of the tyres at the end (when all tyres are entered). I do this because the user could go back in the flow to correct some information, but then the record was already created and this would mess up dataquality from my understanding.

So what I would like to achieve is some kind of map or array, where I could enter as many tyres as I want, and then in the end loop over it and create those tyre-records one by one.

In that case, my visualforcepage could also loop over my array and show all the tyres correctly and not only the last entered one.