I'm not quite sure what this means, but your profile proves you're not a spam bot, so I guess I won't flag it... did you submit this in the wrong tab or am I missing something?
I’m guessing they meant that it would require a good carpenter to make a room exactly 3m x 4m x 3m
How would it be harder than to make a room exactly 10 feet x 12 feet x 8 feet?
I'm guessing they are from the US where carpenters work with feet and inches rather than with meters.