Can somebody show me an example of the feature "Mold" use?

If by mold you mean "mold tools" then here is an example. The model I show is very simple. Molds can get much more complex, but the steps remain pretty much the same. So... start with simple. Even simple take many steps. I have attached the model file in roll-up, so you can step through to see how it works.
Hope this helps. PS SW also has a tutorial on their help page as well.

  1. Step 1:

    1: Part. Cup with hole in bottom

  2. Step 2:

    2: Mold tools

  3. Step 3:

    3: Parting line

  4. Step 4:

    4: Select face

  5. Step 5:

    5: See results

  6. Step 6:

    6: Parting line established

  7. Step 7:

    7: Select Shutoff

  8. Step 8:

    8: Shutoff complete

  9. Step 9:

    9: Shutoff completed

  10. Step 10:

    10: Select parting surface

  11. Step 11:

    11: Establish parting surface

  12. Step 12:

    12: Parting surface

  13. Step 13:

    13: Select tooling split

  14. Step 14:

    14: Select plane

  15. Step 15:

    15: Create sketch

  16. Step 16:

    16: Features created

  17. Step 17:

    17: Mold created

  18. Step 18:

    18: Mold in section.

    ENJOY...

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