Without context, my interpretation is "the target of a build", by which I mean the final output file of a build script.
When using gnu gcc compiler, for example, the default output executable are named "a.out".
With microsoft visual studio's compiler, the default output executable will take on the name of your project with ".exe" appended to the end, such as "my_project.exe".
In these examples, "a.out" and "my_project.exe" are the ultimate goals of your work, and are called build targets.