Ishwaku usually refers to Ikshvaku in Jain texts. Here is the simple Jain understanding:

• Ikshvaku (Ishwaku) is the legendary ancestor of the Ikshvaku dynasty. In Jainism, the first Tirthankara Rishabhanatha is described as belonging to the Ikshvaku dynasty, and Rishabhanatha himself is sometimes called Ikshvaku or the founder of that lineage.
• This dynasty includes famous figures like Bharata and Bahubali, who follow Rishabhanatha in the Jain tradition.
• There is no major difference between Digambar and Shwetambar views on the basic idea: Ikshvaku is the name associated with the early Solar dynasty and with Rishabhanatha as the first ḍārī (lineage) patriarch.

If you’d like more context in simple terms, I can summarize the key points from Jain narratives about Rishabhanatha and the Ikshvaku lineage.