Updhaan / Updhaan is a Jain spiritual observance and tapas, usually done as a disciplined vow-based practice to deepen devotion, scriptural learning, and self-restraint. It is often connected with reciting and mastering sacred Jain texts and mantras, especially in preparation for deeper religious study and practice. ( jaingpt.org)

In simple words, it means a structured religious penance in which a Jain devotee follows specific rules, routines, and recitations with focus and purity of conduct. ( jaingpt.org)

If you want, I can also explain the full Updhaan vidhi or the meaning of Updhaan in simple Gujarati/Hindi.