This text starts a new section on the topic of Action without Reaction. This section continues to Text 24. The topic sprouts from the previous section, especially texts 14 and 15, wherein Krishna mentions that he and other great souls interact with the material world, yet remain uncontaminated. In the upcoming verses, Krishna explains how one may also do so.
Kavayao api atra mohitah - Even the scholars are confused
The first statement Krishna makes on the subject of action and reaction is that it is extremely complex, bewildering even the most learned and thoughtful persons.
Pravakshyami - I shall instruct you
If even the greatest thinkers are bewildered by the subject, who can explain it? Only Krishna can explain it properly, since he is all-knowing (veda-sarvani - see Text 5)
Mokshyase ashubhat - Liberated from misfortune
If one hears carefully from Krishna and understands the subject, the result is liberation from all misfortune.