Doctor told my wife you have 12 days remaining to delivery. when she go to other female doctor she give a tablet and sudden pain begin and delivery occure with very pain and a lot stitching . Question : it is good to give Tablet and delivery occur after 3 hours. My wife is every thing normal. Explain me about the tablet importance.

That sounds like how my wife delivered our daughter. Is it good? Well she gave birth didn't she? The usual problem is what she experienced. The child came hard and fast so there was some tearing around the opening. She got that stitched up.

What the tablet does is prepare your wife and get things doing for birth. Given your shaky understanding of English I will keep this simple. The tablet probably opened the cervix and started the uterus contracting. The child was then pushed out. If they didn't give the tablet there would have been complications if the child when too far beyond their due date. This could have been dangerous for your child and your wife.

Everything is good. Enjoy your family.

One doctor said she had 12 days left... when did she see the other doctor who gave her the tablet? Did she still have some days left before her due date? Did the doctor explain why she was giving your wife the tablet; why she felt the baby should be born soon and not wait?

Sometimes it can be necessary to start the labour if there is a medical reason for baby to be born. Were you and your wife given a reason?

Delivery dates are of course estimates, and I am not sure, how they determined 12 days. The pill it appears would have started the delivery process.
Not uncommon.