lexical means: relating to the words or vocabulary of a language.

this simply means how you cannot use the 'this' keyword within curly braces.
with the fat arrows, you can use this keyword from the current class
i always had a hard time how to get over this challenge, but with ECMASCRIPT
you dont have to worry about it

if you need to put some code here i can, but the video shows exactly how to do it, i like it beacuse its not very long. its a short video and straight to the point

this video explains about lexical this.
ES6 and Typescript Tutorial - 11 - lexical 'this'