The quote you have identified comes from Act I scene 3, and is said by Rosalind to Celia, following Celia's suggestion that they escape the court together and go to the Forest of Arden. If we have a look at the quote in context, it will help us explain what Rosalind is trying to suggest. Note how she responds to her cousin's idea:
Alas, what danger will it be to us,
Maids as we are, to travel forth so far!
Beauty provoketh thieves sooner than gold.
Rosalind is thus greatly afraid of Celia's suggestion, because of their status as virgin "maids." The quote you have identified thus refers the way that virgin beauty often provides a greater temptation than gold to surly, rough thieves, who would be greatly attracted by the prospect of attacking, and, it is inferred, raping such beautiful young women as Celia and Rosalind. Thus their beauty would "provoke" thieves even more than if they carried vast quantities of gold with them.