Simplify the following text for a Grade 6 native English-speaking person.
Original: A time horizon , also known as a planning horizon , is a fixed point of time in the future at which point certain processes will be evaluated or assumed to end .
Simplified: A time horizon is a future point in time when something must be `` done '' ( a `` deadline '' ) or will be `` over '' ( a `` time limit '' ) . Either way , the matter will be closed when the time horizon is reached .