An m² is just a meter squared meaning a 3x3 tent or an area of that size, one plant can cover the whole m² if you veg long enough & train the plant to do so, but you can do more than one plant cutting your veg time down So if you chose to do 16 plants you wont have to veg at all an can do 12/12 from seed and expect to get the yield listed as long as you care for them correctly.