"Foot" is singular, "feet" is plural
Foot and feet are the singular and plural version of the same noun. So it would be 1 foot but six feet etc.
foot is onefeet is more than one
A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′ - the prime symbol) is a non-SI unit of length For example, 2 feet 4 inches is denoted as 2′4″.
Nothing that's just singular or plural.