As can be seen from the photograph of the model of a scapula bone (part of a model of the human skeleton) on the right, the scapula bone is approximately trianglular. It is described as a "flat, triangular bone" so one would expect it to have three "angles". They are:
These three "angles" of the scapula are apparent from the two diagrams below and on the diagram of the 3 angles of the scapula bone.
The anterior angle of the scapula is at the thickest part of the scapula and forms a feature called the head of the scapula that includes the articular surface called the glenoid cavity.
The head of the scapula is surrounded by a slightly depressed surface called the "neck" of the scapula which can be seen (but isn't labelled) in the following diagrams.