What does Devansh mean?
A compound of Sanskrit देव (deva, 'god, divine') + अंश (aṃśa, 'portion, part'), read as 'a part/spark of God'. The elements are genuine Sanskrit, though the compound itself is a modern coinage used as a name rather than a classical term.
What does Ishan mean?
From the Sanskrit ईशान (īśāna), 'ruler, master'. It is an epithet of the god Shiva, also denotes the sun and the north-eastern quarter (one of the dikpalas). A genuine, well-attested Vedic/classical term.