Translation
If the scourge sprouts in order to be a spreading sprout
Go to footnote numberon the skin and [if] the scourge covers all the skin, the mark being from his head to his foot, every place the priest sees,
Paraphrase
If the skin condition spreads so as to take over the skin and if the condition covers all the skin with the visible evidence of the condition being present from head to toe, or at least everywhere the priest is able to see,
Footnotes
1
The same verb is used twice but in different forms, one of which is an infinitive. It means “to blossom, to sprout, or bloom” and it was also used to indicate spreading or breaking forth. Here the text is using the word sprout to communicate spreading.