A Transfer is made up of a couple basic building blocks:
The labware and wells you want to aspirate from
The labware and wells you want to dispense into
When to get a new tip
Which motion to use to perform the Transfer. We call this "Path".
The Protocol Designer can only interpret specific ratios of source : destination wells.
1-to-Many. Select one source well and multiple destination wells.
N-to-N. Select any number of source wells, and an equal number of destination wells. If the numbers are not the same an error will be produced.
Many-to-1. Select multiple source wells and one destination well.
Tell the robot when it should get new tips. The options here vary depending on what well ratio you have selected. Read more here.
i.e. If you are performing a Many-to-1 Transfer (and therefore only have 1 destination well) then you will not have the option to get a new tip for each destination well.
Sometimes your pipette size and Transfer volume are such that multiple transfer volumes can fit inside one tip. If that is the case then you will have the option to use a multi-dispense or a multi-aspirate. Read more about the various paths here.