The question does not mention the language in which that specific book is written. However, in German academic writing, the reference
(Harding, 274f.) would refer to pages 274–275 in a publication by Harding listed in the bibliography or references. (The publication may be a book or an article, but there would be only one by "Harding", otherwise, the year of publication or some other information would need to be added to disambiguate the reference.)
(Harding, 274ff.) would refer to pages 274, 275 and 276, whereas a reference to a larger number of consecutive pages tends to be written as, e.g.
(Harding, 274-77.). (Admittedly, conventions can vary a bit.) The "f" stands for "und folgende [Seite]" (literally "and following [page]" and "ff" for "und folgende [Seiten]" (literally "and following [pages]").
In the English-speaking world, "f" and "ff" are sometimes also used, in which case "ff" may refer to an unspecified number of pages rather than just two. For example, the ACS style guide (by the American Chemical Society) writes (in chapter 14):
You may also indicate pagination in reference citations by “f ” or “ff ”, which
mean “and following” page or pages, respectively. The f or ff is set in roman type
and is spaced from the preceding number:
- 60 f (indicates page 60 and the page following—pages 60 and 61)
- 60 ff (indicates page 60 and pages following)
- 58–60 ff (indicates pages 58 through 60 and pages following—essentially the
same as 58 ff except that the three pages enumerated contain the most pertinent
information and other relevant information is scattered on the rest of the pages)
There are contexts in which "f" may stand for "folio" in the sense of "folio-size edition". For example "F1" can stand for (Shakespeare's) First Folio, "F2" for the Second Folio, etcetera, but in Shakespeare's case, this went up to "F4; there definitely weren't 274 of them. The first folio edition of Ben Jonson's works was published in 1616 and probably inspired the first Shakespeare folio.
In other contexts, "f" can stand for "leaf" (i.e. the size of leaf that the "folio editions", above, are named after). For example, Eugene Giddens's How to Read a Shakespearen Play Tex contains the following example of a speech heading from Ben Jonson's Poetaster followed by a reference (page 87):
Hora. Tibv. Gall. Mecoe. Virg. And thanks to Caesar,
That thus hath exercis'd his patience.
In this case, Ff6 refers to the sixth leaf (6f) in Ben Jonson's Folio edition (F) of 1616.
However, in references such as "(Harding, 274f.)", I assume the intended meaning is page numbers, not folio editions or folio leaves.
- Coghill, Anne M.; Garson, Lorrin R. (editors): The ACS Style Gudie: Effective Communication of Scientific Communication. Third edition. Washington: American Chemical Society, 2006.
- Giddens, Eugene: How to Read a Shakespearean Play Text. Cambridge University Press, 2011.