There may be more than one acronymn for RFP. But if you're a business it usually means Request For Proposal.
In general, it is a form that you have a prospective client fill out, so that your company can quote a proposed selling price for your product or service, based on the information the prospective client fills out.
That may seem straight forward enough, but the process of creating an effective RFP is actually pretty tricky.
For a company to respond to a RFP, the form has to be submitted to the company. That usally means that it has to be written well enough so that the prospective client actually finishes the form and submits it (whether they submit it via the internet or the postal service).
How you word the form depends primarily on the company's target market, their dependence on RFPs, the sales force, and their attitude towards (generally unsolicited) clients.
Steve