When you've posted a job ad to multiple job boards and websites, you want to be able to see how many applications are coming from each source.

In 50hire, you can see the traffic sources under job -> Statistics, here you can see an example:

Note, that this statistics is based on from which site the applicant came when s/he applied. If the applicant first saw the ad on a job board, but then a week later s/he went directly to your website, that applicant will be registered as coming directly from your website. This can however give you an idea of the performance of each job board you post to.