The word form of a number, also called word name for a number or written form, is the number written in words.
More examples
The word form for 16 is sixteen.
The word form for 2/5 is two-fifths.
The word form for 9.4 is nine and four tenths.
The word form for 2018 is two thousand, eighteen.
The word form for 2,150,045 is two million, one hundred fifty thousand, forty-five.
Notice that for 5.6, the decimal point is read as "and" and for 2,150,045, the word "and" is not included in the word form.