What is nvidia how it improves my VGA

Let me tell you something.

First, I know that you don't know what is a GPU (Graphic Processing Unit) Cards.
A graphics card, is a card that is put on the PCI-E slot on your motherboard mainly used to boost our integrated graphics. We use to call them 'dedicated' ore 'discrete' graphics because the card itself is only for graphics.

This is why the thing is why dedicated cards is better than integrated graphics, so therefore Graphics card will boost your performance. But don't compare something from 10 years ago and current, because that will be different.

And in the second, what is Nvidia:
Nvidia is an American global technology company based in Santa Clara, California. Nvidia is best known for its graphics processors (GPUs). Nvidia and chief rival AMD Graphics Technologies (formerly ATI Technologies) have dominated the high performance GPU market, pushing other manufacturers to smaller, niche roles. Nvidia's best known GPU product line labeled "GeForce" is in direct competition with AMD's "Radeon" products.