The lease you are googling is probably from usa, in usa lease means finance the car for 3 years and 36000 miles, the residual value is predetermined at start of lease and lessee can choose to buy out the car at the RV with a balloon payment, meaning lumpsum.
The word car lease in Pakistan is called financing, change your search terms and you will get the idea.
What happens in uk and usa in lease is non existant in Pakistan.
If they are talking about a baloon payment at end of term then obviously this would have more terms like odometer limit etc.
Which i dont think so is existant in Pakistan as the risks are too great,
So ask them for a total, interest and principal total that you financed and how your installment services it.