Here is the basic idea of the Atichar you hear in Samvatsari Pratikraman:

• Atichar means a confession of minor transgressions or deviations from the ideal conduct that Jain laypeople try to follow during the year. It is a structured prayer to acknowledge these small faults, seek forgiveness, and resolve to improve.
• In Samvatsari, the Atichar section (Atichar Gāthā) specifically lists the kinds of faults that are commonly confessed. These relate to misdeeds or lapses in the five key areas of Jain practice (knowledge, faith, conduct, penance, and inner strength) and the related vows and moral disciplines. The verses guide the practitioner to admit shortcomings in thoughts, speech, and actions, and to ask forgiveness from all living beings.

• There can be slight differences between Digambar and Śvetambar recitations in wording, but the essential purpose remains the same: confession of faults, seeking forgiveness (Michhami Dukkadam), and renewing vows for the new year.

If you want, I can provide the exact verse text used in the Atichar section and explain each line step by step.

You can read more here