This is the fraction an employee on this work pattern who works compared to a full-time employee in this role.
Normally, this would be calculated by dividing the Contracted Hours per week by the Full Time Hours per week on this pattern.
FTE is calculated based on the contracted hours and full-time hours values entered in the planner settings. If you want to change it you'll need to amend those values.
An FTE value of 0.50 would represent that the employee works 50% of the hours that a full timer in the same job would work.
Similarly, an FTE of 1.00 would represent that the employee works 100% of the hours that a full timer would work in the role.