The basic setting of the ignition is something you have to do to get the engine to run in its basic setting, which is needed to get the engine running at all, especially if the distributor has been removed, for example because the cylinder head had to be removed.
1st turn the engine on the pulley until the mark (a round point) on the right side and bring it exaxtly between the two metal marks like shown in the window.(red marked)
2nd Turn the removed distributor to its basic position and make sure that it is not accidentally twisted during installation. It is important that the marking on the right side corresponds to the picture here and on the left side also the marking (not to be confused with the rivet which is also inside there).
This approached line is the edge from the manufacture of the manifold.
In reality, this is what it looks like:
Simply bring this "edge" into line with the equivalent edge on the cylinder head. Make sure that the distributor is not twisted.
And so you can start the engine, it must work. If not, there is another error.