Time, like Versions, is a built-in dimension that all models have by default. Model builders use Time to structure data in modules. 

For example, you can use Time to analyze past data, and to plan for what might happen in the future. You can also use the Time dimension to create "what-if" scenarios to achieve a specific outcome.

You can remove Time if you do not require it in a module.

In Time in the model settings bar, you can set the calendar for your model, and create time ranges. Use time ranges to plan for an organization over different years from the model time scale. 

For example, if your model time scale is set to the current year, you might also have a time range with 10 future years for long range planning.

If you edit any settings in Time , it affects the entire model.