The term “script” has different senses. In modern day computing parlance, its reference to short programming codes has become more common. It also popularly connotes to the screenplays for drama, film etc. In cases, it also implies written documents e.g. manuscripts, typefaces in style of handwriting, handwriting as opposed to printing.
But, for written communication, script denotes the “system of writing adapted to a particular language or set of languages”. (wikitionary). It is the set of written characters or symbols used to represent oral language in written form.
The definition from Unicode Consortium’s glossary is relevant at this point:
Script: a collection of symbols used to represent text in one or more writing systems.
Scripts are the actual sets of graphemes used to write languages. https://www.llas.ac.uk/resources/gpg/2662
Scripts are the character sets used in written languages. The character sets essentially consist of graphemes, commonly termed as letters, characters, glyphs, signs, akshar etc.
For example, English alphabet consists of letters; Chinese Hanzi consists of characters, Maya script have glyphs, cuneiform signs, Devnagari aksharmala consist of Akshars.