Russian Perfective Verbs refer to those actions which are complete, or one-off in nature. For example - "I wrote a letter (to completion)" is a perfective action, while "I was writing a letter" is an imperfective action, as it does not denote completing the action.
This page lists the most important Perfective Verbs. The table outlines phonetics, as well as the conjugation pattern required (this is indicated by the number 1 or 2). Remember that perfective verbs cannot be used in the present tense.