tbb12.dll
This file is not a system component: the program that uses it, not a download. Restore it from the source that installed it rather than downloading a replacement.
If the file is already there and Windows still complains, read the message again: “entry point not found” is a different problem from a missing file, and installing the runtime again will not solve it.
Do not download this DLL on its own
Searching for a missing DLL by name leads to sites that hand you that single file. It is one of the oldest and most effective malware delivery methods there is, and a system DLL from an unknown source is indistinguishable from a deliberately modified one. There is never a legitimate reason to obtain a runtime component that way.
The same goes for the tools that offer to do it for you: what a DLL repair tool can and cannot actually fix.
What it is
The runtime of oneTBB, the threading library formerly known as Intel Threading Building Blocks, which applications use to spread work across CPU cores. The 12 is the library ABI version, not a year or a product edition.
Where you see it: 3D, rendering, CAD and photo software, which bundle it to parallelise their heavy work. Also after moving a program folder between machines without reinstalling it.
oneTBB is shipped inside the applications that use it rather than installed once system-wide, so the copy that matters is the one in that program’s own folder. Reinstall or repair the application and it comes back with the build the developer tested against. Mixing in a tbb12.dll of a different version is a real risk here rather than a theoretical one, because this is a threading library and a mismatched build tends to produce crashes that look like bugs in the application instead of an obviously wrong DLL.
Why there is nothing to download here
There is no verified download we can offer for this one, because installing a file is not the fix. The steps above are what actually resolves it. That distinction matters: the sites ranking for this file name are selling a download that would not have helped even if it were safe.