WP_Query is a way for WordPress to get your posts or custom posts. A repeater is a custom field that you can add inside posts, custom posts, options page, etc. So you can use WP_Query to get the posts you want and then get the repeater inside that posts using have_rows() function. This page should give you more idea about it: http://www.advancedcustomfields.com/resources/repeater/
I hope this makes sense.
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