The only reason a metre would need to be called a "linear metre" is to distinguish it between a "square metre" (1 metre in length timesed by one metre in width) and a "cubic metre" (1 metre in length timesed by one metre in width timesed by one metre in height).

Therefore, one linear metre is the same measurement as one metre.

A metre cannot be converted to a square metre. A metre is a length and a square meter is an area.

It is 1 cubic metre.

1/4 of a metre is 25% of a metre

A linear (lineal) metre is the same thing as a metre. I think it's a dumbed down term for a metre so people won't get confused with metre, square metre and cubic metre.