RPRF is the second portion of the CEC fee (it is $490) that you'd have to pay before the PR visa can be issued. Has to be paid by principal applicant and spouse, if applicable, but not minors have to pay. If you got MR and everything is good, the RPRF request should follow shortly. Biodata is a short form requesting info like height and eye color that usually comes in the same email as RPRF request.
After all that is complete and sent back to CIC you wait for the decision to be made, and either get Copr (for visa exempt countries) or PPR request to submit your passport for visa stamping.