As humblepm said, a project objective is a sentence, but note that one project can have multiple objectives, for example, here are a few objectives in a single construction project:
- Create 48 state of the art luxurious and "smart" apartments
- Create a 10 show rooms that will attract global companies
- Create several amenities in the building such as a gym, a heated pool, and a nursery.
Project objectives must be clear and must represent clear, executable deliverables and not just a "vision" (which is the case of project goals).