What is setTimer's time unit?

What is the unit of the float paramter time in setTimer? is it in seconds or milliseconds or something else?

Also I was looking at AGameMode’s default timer and it seems to be setting timer on EffectiveTimeDilation which is generally when there is no matinee or other things playing, Does that means the default timer would be called every second?

Seconds

DefaultTimer is called once per second, yes.