Flow variants are saved filter/parameter values which can be reused. Flows with tasks using user variables will show selection pop-up for the variable values. User specifies values for these variables to run the flow.
Take an example of a Netsuite Query task that uses 2 variables - user will specify these values at runtime.
A flow executing this task will show like this:
This particular selection (Account type = ‘Bank’ and Date = ‘1/ 1/ 2023’) can be saved as a variant (Save this variant link at bottom of screenshot) so it doesn't need to be keyed in again. ‘Select a variant’ option in screenshot above provides a drop-down of already saved flow-variants and users can choose from that list instead of typing the values in.
Other use of flow-variants is when a flow needs to be run in batch for different values (let us say a flow is run for a month at a time due to API limitations). Flow-variants for month values can be saved for the same flow (say 12 flow-variants for one year). In batch scheduled run, user can specify all these flow variants of the flow, and one schedule can run the flow 12 times - once for each flow-variant selection.