As you can see intro text shown in this module is justify aligned. You can easily setup any other style and class for each layout. But if you use the same layout in two module instances, then the styles will be the same, you should use a different layout in order to have different styles.
This module is based on layout no.3. For each layout, module is using a different CSS file so you can style your module separately from the other modules in page. In order to change CSS classes, you just need to open css file located at modules/modarraarticles/layouts/ which is named Layout_3.css and add your style in already created classes.
This is another K2 item for testing purpose. On each module you can choose from 8 layouts and you can also choose how many columns to show in front. If you choose one column and have two articles, then you will have also two rows. If you choose 2 columns, then will be only one row, so you can manage module layout as you want.
This is a sample of module based on K2 items.
When you copy an already created module and start to create a K2 one, please first delete any Item ID's that are in place from original module. Then, just click on Select Items link and start to add K2 Items - click on Item title and will be automated added to the list. Or you can use Category or Featured selections in the list.