This is a rather crunchy topic with a lot of stuff to learn. Please use these resources to assist you complete your workbook

Metalanguages like EBNF and Railroad diagrams

This is the most succinct presentation I have on EBNF and Railroad diagrams. You may notice it is the same pressentation and video is used in the HSC course at this point too. There's a good reason for it. It's that good. Credit to Francisco and Melinda who made the presentation in 2019 and narrated the YouTube version too.

The syntax used to represent control structures

The syntax used to define data types