Breakdown of Die regel is heel streng.
zijn
to be
heel
very
die
that / those (de-words and plurals)
de regel
the rule
Questions & Answers about Die regel is heel streng.
Why do we use die instead of dat for 'that'?
We use die because regel is a de-word (de regel). If it were a het-word, you would use dat to say 'that'.
I thought heel meant 'whole'. Why does it mean 'very' here?
You are right that heel can mean 'whole'. But when placed directly before an adjective like streng, it means 'very'. You could also use erg here (erg streng) to mean the exact same thing.
streng looks like the English word 'strong'. Do they mean the same thing?
They are false friends! streng means 'strict' or 'severe'. If you want to say 'strong' in Dutch, you need the word sterk.