I make it a point to study English for three hours every day.
Literal
Every-day three-hours English [object-を] study doing [nominalizer-こと] [goal-に] am-doing.
~ことにしている means 'I make it a rule to / I have decided to (and continue doing).' It combines ことにする (decide to do) with ている for an ongoing self-imposed practice. Distinct from ~ことになっている, where the decision comes from outside.