Namaskar. “10 days of das” is not a standard, universally used phrase in Jain Dharma. It could refer to a few different Jain concepts that involve the number ten. Here are the most likely possibilities:

• Das Lakshana: the ten essential attributes/virtues that describe a Jina or a liberated soul (e.g., auspicious qualities like truth, non-violence, restraint, etc.). This is often taught in Jain philosophy as a summary of a perfect state.
• Das Parshva or Das Avatara (less common in Jain contexts, sometimes mentioned in commentaries): references to ten aspects or figures in certain Jain texts, though not a fixed ritual.
• Ten vows or tenfold discipline in some monastic lineages (a simplified or regional teaching variation): often discussed in the broader context of Jain ethics and conduct.

If you can tell me which of these you have in mind (or share a bit more about where you saw the phrase), I can give you the exact artha (meaning) and, if requested, the original text and the Digambara/Shvetambara nuances.