whats this thing and whats the effect of a broken one??

hi guys,

1990 M20 5251 manual.

There is wire and "coil" attached to the #1 spark plug lead.

The wire has broken off and you can see a kind of magent wire wire wrapped around it inside.

what does this do and what problems would it cause if it is broken and not doring what it is supposed to? Is it some kind of ignition timing thing?

Thanks.