My MacBook Pro graphic card doesn't support Samsung monitor

2nd Display Support: Dual/Mirroring

2nd Max. Resolution:2560x1600

Details:The maximum resolution supported on an external display is 2560x1600.

from:

https://everymac.com/systems/apple/macbook_pro/specs/macbook-pro-core-i7-2.3-15-mid-2012-unibody-usb3-specs.html

Your Mac is 8 years old. At the time it was released, it could support an External display at an amazing 2560 by 1600, and Apple was one of the few makers of a display so large. But in the fast moving world of computer technology, that is not considered so large today.

There are no upgrades anyone can perform on your old MacBook except to upgrade the RAM memory or the Storage. All the rest of the components are soldered to the mainboard. In the next version of your computer, the RAM memory was soldered down and un-upgradable as well, and in still later versions, the boot drive was soldered down and not upgradeable.

The display you suggest looks to be a 5K display, It can be drive by your computer at 2K, but can not be driven at its full resolution by the computer you own now.

This is a similar problem to owning component stereo equipment. Once you upgrade one part, you need to upgrade more to take advantage of all the features.