Hello everyone, i have a problem...and i'm lost

I have 3 categories with articles in each of them, within each category I show the "category description" and the articles. So far everything is correct, but I need to show the 3 categories together but using as a separator the description of each category as follows

Description category 1
Article 1
Article 2
Article 3
Description category 2
Article 1
Article 2
Article 3
Description category 3
Article 1
Article 2
Article 3

I've managed to show the articles of the 3 categories, but without the description as a separator.

Article 1
Article 2
Article 3
Article 1
Article 2
Article 3
Article 1
Article 2
Article 3

What I can do? please help

if i select one category it shows the description, if i select two categories it doesn't show description.

:-(

Thanks! It is already shown, but ... it does not show with the template that I want, although I select it, it does not show it well.

solved! Files "latest_item" and "latest" were missing. Once created and modifying the code it is already shown the same.