Your plan lists six meals a day, each with a food and a quantity. Quantities are given in household measures — a cup, a piece, a tablespoon — with the weight in grams beside them, so you can use either.
Swaps
A food can be swapped for another in the same group and roughly the same quantity: one roti for one small bowl of rice, one fruit for another. If you are unsure, ask — that is what the weekly review is for.
When a day goes wrong
It will. Eat the next meal as planned and move on. One meal does not change a week; a week of skipped meals does.