What does yarsu in ancient Egypt mean?

Answer 1

It is difficult to know which word you mean without seeing the hieroglyphic version. Hieroglyphs did not record vowels, so the "a" and the "u" can not be correct; this leaves yrs, but there is no such word in Egyptian.

If you substitute w for the u, you get yrsw, but there is still nothing like that in Egyptian.

Leaving out the y, you get rsw and there are many different words written in that way:

rsw + the "town" determinative = the south land

rsw + the "sail" determinative = the south wind

rsw + the "eye" determinative = to watch, to guard

rsw = vigilance (connected with previous word)

Answer 2

It is the king at one point in time :)