Key Characteristics:

Field Size: 
40m x 23.7m (Standard Competition)MarkingsDesigned to be minimal, a half way line and 10m mini-lines create 4 equal sized quarters of the field, plus penalty spots (6.4m from the goal-line) are the only required markings

Equipment:
2 goals, each 3.66m wide and 2.14m tall (Standard Hockey Goals)

Each player uses a hockey stick made of any non-metallic material with a maximum length of 105cm (41.3inches). Sticks are usually sold in lengths in inches with 36.5 and 37.5 the most common adult sizes. Only the flat side of the stick may be use to play the ball. (Standard Stick)

PPE (Personal Protective Equipment) for field players includes shin-guards and mouth-guards.
Goalkeeper PPE includes kickers, leg guards, padded shorts, body armour, gloves, neck protector and a helmet.

Key Skills:
Players may push, slap, hit and flick the ball both forehand and backhand (Same as 11-a-side Hockey)

You can watch a video overview of the concepts here.
Watch a full game here.
You can read more about Hockey5s here.