For Leave Types which are encashable, you can submit Leave Encashment. To create a new Leave Encashment, go to
Human Resources > Leaves and Holiday > Leave Encashment > New Leave Encashment
As you select Employee and Leave Type, Leave Balance and Encashable Days (which is total leave balance less the threshold days set in Leave Type) will be shown along with the Encashment Amount based on the Leave Encashment per day as configured in the Employee's assigned Salary Structure.
On submitting a Leave Encashment for an Employee, ERPNext automatically creates an Additional Salary which will get added to the Salary Slip of the Employee when processing the next payroll
Next: Leave Ledger Entry