Goal is a generic statement. Objective should be a specific step taken towards the goal and KPIs are a way to measure the objective.
"Excel in academics" is a goal. "Score above 80 in Maths" is the objective. "# of times you scored above 80 in Maths in 4 tests conducted in a given year" is a KPI. The KPI can have an acceptable range. Scoring above 80 each time is excellent, while 3/4 is also very good.
