Well, i understand measurements, i'd like to understand what does that actually means - perhaps a number and length of the distribution pipes, etc - more like the physical layout of the bed.

Long and skinny or short and wide, 14 square meters either way. Actual layout depends on site conditions, what pipe the contractor has, etc. The design engineer has determined that for your house and the types of soil condition present, the leach field needs to be 14 square meters in area. That's all.

The information you are lookin for is available on the internet.

google: septic leaching field requirements.

Do want to have a forum based discussion or are you new to the internet?

"Well, i understand measurements,"

And yet you asked what an area measurement meant? Moronically, I might add!

14 square meters in area is not large enough in gross size for a leach field. It's not even large enough in metal area of trenches. So it must have a different meaning or a mistake.