Training in 3D
Your muscles and joints work through every conceivable angle so your training should reflect this.
There are three planes of movement defined as:
Any explanations I have found on this topic tend to be quite complex (or ambiguous) so I will make this as abstract as possible.
Each plane has two distinct directions:
The Coronal (or Frontal) Plane works with side-to-side motion such as a side lunge, jumping jacks and overhead press.
The Sagittal Plane incorporates forward and backwards motion such as press-ups, forward lunges and squats.
The Transverse Plane involves rotation at the hips, for example swinging a golf club, floor-to-overhead diagonals with a kettlebell or a transverse lunge.
Most training tends to be single-plane working predominately in the Sagittal plane with occassional references to the other planes. In real life it is rare you restrict yourself to one plane, for example sprinting involves all 3 planes to varying degees. Mixing things up and training in multi-planes will reduce muscular imbalances, improve joint mobility and help to avoid injury.
To be honest you dont need to know what thes terms mean or what axis of movement they correspond with. But it does help to understand what they can mean to your programme. Just be mindful they exist, use your imagination and add another dimension to your training. Go and explore 3D.