Payment in kind. The idea behind this is repaying like with like (like in the sense of "podobné"), so if someone does a good deed (skutok) or a favor (láskavosť) and they are repaid in kind, not with money, but they enjoy a good deed or a favor in return. There is a saying: One good deed deserves another. This also applies in a negative sense, though, because a trick or a swindle can be repaid in kind.

This is "kind" in the sense of "druh", not "milé" or "ústretové" - the positive meaning developed from the expectation that family members (kin) should be well-disposed towards each other. Repaying bad with bad is the English idea of revenge (payback - see the Mel Gibson film), so there's another tricky word, because it sounds like the Slovak "na revanš", but I understand that as something positive, like returning a favor, inviting somebody back, or buying the next round of drinks.