John Gill Commentary 2 Chronicles 35:7

"And Josiah gave to the children of the people, of the flock, lambs and kids, all of them for the passover-offerings, unto all that were present, to the number of thirty thousand, and three thousand bullocks: these were of the king`s substance." — 2 Chronicles 35:7 (ASV)

And Josiah gave to the people, of the flock, lambs and kids,
all for the passover offerings
Which are either lambs or kids of the goats, (Exodus 12:5), for all that were present, to the number of 30,000; that is, 30,000 lambs or kids, which would serve 30,000 families:

and three thousand bullocks ;
these were for the "chagigah" or feast, kept on the day following the passover:

these were of the king's substance ;
taken out of his flocks and herds, or bought with his money, and liberally given to the people, to such poor families as could not afford well to be at the expense of such a festival.