hi,
how can I show extra field content in module?

thanks a lot

Simply select extrafields to be visible under the K2 Content module's params.

I can see an option to show extra fieldes in the Module K2 content - but not a spchfic extra Extra field...
can you send me an image?

If you want one extra field to appear then you have make a new K2 Content template for that module.

This post has the snippets you need to c/p and explains the logic behind extrafields.
getk2.org/community/English-K2-Community/171284-Where-to-edit-K2-after-Item-Fields

This tutorial will help you with overriding.
getk2.org/documentation/tutorials/174-templating-with-k2-and-the-concepts-of-sub-templates