Suggestion

Co-authored-by: Anton Trunov <[email protected]>

pages/book/expressions.mdx

@@ -88,7 +88,7 @@ Read more about strings and [`String{:tact}`][p] type there: [Primitive types][p
 
 ### `null` literal
 
-The `null{:tact}` value is written with a `null{:tact}` literal. It's **not** an [identifier](#identifiers) and doesn't refer to any object. It's also **not** a [primitive type][p]. Instead, `null{:tact}` represents a lack of identification and the intentional absence of any value.
+The `null{:tact}` value is written with a `null{:tact}` literal. It's **not** an [identifier](#identifiers) and doesn't refer to any object. It's also **not** an instance of a [primitive type][p]. Instead, `null{:tact}` represents a lack of identification and the intentional absence of any value.
 
 ```tact
 let var: Int? = null; // variable, which can hold null value