The conga rhythm Wikipedia identifies as helpful for learning salsa contra-tiempo, or On2, is tumbao.
Tumbao is a foundational rhythmic pattern in Afro-Cuban music, especially when played on conga drums. In salsa, its basic pattern commonly falls on beats 2, 3, 4, 6, 7, and 8 of an eight-count cycle, giving the music a strong offbeat character.
That emphasis makes tumbao useful for On2 dancers, who break on beats 2 and 6 rather than the more familiar On1 timing. Listening to the conga pattern can help dancers feel those accented points and maintain the direction of the phrase.
The distractors refer to real salsa terms but do different jobs. Martillo is a repeating bongo pattern, montuno usually describes a looping piano figure, and bembe refers to an Afro-Cuban religious and musical tradition rather than this standard conga rhythm.