This means that the instead of fixed width integer types that have a finite maximum due to being 32-bit or 64-bit etc…, the language could use an integer type t

This means that the instead of fixed width integer types that have a finite maximum due to being 32-bit or 64-bit etc…, the language could use an integer type that can grow to be as many bytes as is needed to store the number. This is called a BigInt in JavaScript for instance.