A layout defines the text and images that will be printed on to the card and where it will appear.
A profile is a set of "adjustments" applied to a given template just prior to printing which compensates for anomalies unique and peculiar to a given printer (to which the profile is assigned). This means if you set a template up and then print a sample set of data and find that the items are not all aligned the same on each card, you need to set up a profile for each printer to make up for the differences in printing styles, such as the shifting of text to the left, right, top or bottom.
A template is the label/card stock you are using. This might be Avery 5160 for address labels, Gaylord 47-284 for spine labels or Avery 28371 for your patron cards, just to give a couple of examples. These labels will include all of the information you will need for setting up a Koha, this information may be on the packaging, and if not it can usually be found on the vendor's website.
To print to a duplex card printer you need a '1 up template' (1 row / 1 column) and for both card sides a separate layout.
A batch is a collection of patrons for whom you want to generate cards.
See the full documentation for the Patron Card Creator in the manual (online).
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