How many liters One feet square?

Answer 1

There can be no equivalence.

A litre is a measure of volume in 3-dimensional space while a square foot is a measure of area in 2-dimensional space. The two measure different things and, according to basic principles of dimensional analysis, any attempt at conversion from one to the other is fundamentally flawed.

If you are thinking about coverage for paint or similar, then there is no simple answer. Paint coverage depends on the paint, the nature of the surface being painted, the preparation and so on. There will be indicative information on the paint tin.