Why are the verbs in pairs?
Nearly all Russian verbs occur in two aspects, imperfective (1) and perfective (2). It's essential to know both aspects of a verb, so Glagoly lists them together, alphabetized by the imperfective (the verb on the left in each pair).
If you're just starting out with Russian and your course has not yet covered perfective verbs, don't worry about them for now. They'll be very important soon enough!
In the main Глаголы tab
In the Tense List screen
In the Tense List screen, the imperfective is on the left of the segmented control (1); the perfective is on the right (2).
Selecting the perfective
Selecting the perfective (1) in the Tense List screen allows you to see forms for the perfective. Since perfective verbs do not express present meaning, the "Present" item in the table disappears (2).