A kosher dill pickle is a garlic-and-dill cucumber pickle associated with Jewish deli traditions. In this name, kosher often describes the style of pickle rather than guaranteeing religious certification.
Some kosher dill pickles are fermented in brine; others are made with vinegar. Check the label or recipe for the method. People who require kosher-certified food should look for an appropriate certification mark rather than relying on the product name.