Pretty self explanatory - this is the list of skills characters may roll against the challenge.
Often, especially for multi-round skill challenges, the DCs for different skills will be in the Low (+0 DC), Moderate (+2 DC), or High (+5 DC) range, and labeled as such if intended to be known.
Other times, such as for Influence skill challenges, a Discovery skill will be listed, which if attempted and successful, will reveal new skills which may be used, and/or give information as to the ordering of which skills' DCs are in the low, moderate, or high range, and/or share new mechanical information about the skill challenge itself.
A note on "non-skill skills": Sometimes I may put "Perception" or certain saving throws inside this entry - just roll those as if they were skills, assessed against the same DC, as normal.
A note on Spells. Familiarize yourself with the Counteract rules - they will come into play here. Assuming the spell you are using would be narratively impactful, and you describe using it, if you expend a Spell Slot, roll a counteract check against the counteract level of the Skill Challenge. If you succeed in "counteracting the target", you will earn a single VP. As you may have guessed, just like "non-skill skills", the counteract DC is the same as the base DC of the Skill Challenge itself.