Definition from Wiktionary, the free dictionary
- "and following" (pages, etc)
- This is short for "folios following," which according to common usage can include pages, paragraphs, Bible verses, or other written material. When reading aloud, say, "and following."
Etymology 1 
Etymology 2 
When pronounced as the plural of 'f', it sounds like the Dutch word effen.
Usage notes 
This abbreviation is primarily used in informal communication, such as text messaging and web messaging.