This conversion is often needed by users that try to convert their bank or credit card statements in PDF format (online printing) to a universal Open Financial Exchange format (.ofx) that can be import in almost all current accounting software.
The most convenient way how to solve this conversion would be to get a specialized utility designed exactly for this task, for example some of the converters from ProperSoft, such as PDF2OFX.
However, most dedicated utilities are commercial hence cost money. So if you want to make it for "free" you can try to use the following, yet not very reliable way how to convert .pdf documents to .ofx files.
First you would need to extract the data from the PDF document to some structured format, for example TSV, but even plain text file format may work for some really short and simple statements. You can do this for example using Adobe Acrobat (Reader) and its export function.
Once you have the text file, you can try to import it to Microsoft Excel or any similar spreadsheet editor. It is likely that the program will ask you to pick what kind of separator the file uses, so it can import it properly to spreadsheet. After that, you can save the file to CSV format.
The last step would be to convert csv to ofx, which you can do in many programs, some of them available for free. But as we said, this procedure may not be always 100% reliable and it would be best to use a direct converter for pdf to ofx conversion to prevent errors.