You asked: what is the difference between weekly and monthly expiry
Expiry, and how an index option settles
Expiry is the date the contract ends, and an Indian index option ends in cash: the exchange pays the difference between the strike and the settlement level, and everything else about the contract stops existing.
Mayawhat these words mean
Maya reads the desk’s written explainers and the glossary. She holds no market data at all, so she can say what a thing is and cannot say what it is doing today.