There is no way to tell. It can mean just about anything.
a gopher or a mole
The fertilizer should go in the topsoil where the grass and plants can use it.
i think it probably means, since snails love to eat the leaves and other stuff of plants, it probably means that they are hungry so they chose your yard to eat off of
See if there is a hole under it....and they wouldn't lay eggs in your yard unless it was near water
no
They will help but they are not the easiest to install. French drains require a ditch be dug around the perimeter of the yard leading to the lowest area for drainage. After laying pipe in the ditch, it is covered with gravel and dirt to secure it.
you can use lots of block wood to make it look like a actual ball yard
There are 9.144 lots of 10 cm.
There are three feet in a yard. This is an important unit of measurement to know if one is laying carpet or cutting fabric.
they mean a closed yard
If you mean 1/36 of a yard then it is 1 inch
If you mean how many feet in a yard, 3. if you mean what you said, its wrong, but its .33333