Hi and welcome:

It is recommended that you count calories for your two diet days each week (no more than 500) and eat ‘normally’ for the remaining five days.

However, most people starting a weight loss diet have been gaining weight, so eating ‘normally’ for them is the same as eating ‘too much’.

The basic rule, then, is to eat 500 or fewer calories on your two diet days, and eat to your TDEE or less on your remaining five days. Number four in this thread will explain TDEE: https://thefastdiet.co.uk/forums/topic/the-basics-for-newbies-your-questions-answered/

Good Luck!