The numbers are meant to help you find the actual image of the census page where the person named is shown, and which also shows the address.

1861 means the census for 1861 (there are censuses for 1841, 51, 61, 71, 81, 91 and 1901. 1911 is in the process of being released but the IOMFHS has no index for that)

If you have access to Ancestry, adding the parish of residence [Braddan] and the piece [4412] & folio [84] numbers on the search page should help find the named person and their address, but they are probably more of a help if you're using fiche or census CDs.

The last number [39] in the index is the household number which is not as useful in my opinion as the page number would have been.

Not sure if any of that helps!