The Oxford English Dictionary (“OED“), Oxford University Press, 2d Ed. (1989), Digital Volume 4.0 (2009) defines “about”—as used in the context of this WordPress template; i.e., “about” definitional entry B.I.7.a—as follows:

about, adv. and prep. (əˈbaʊt)  [ . . . . ]

B. (with object expressed) prep. I. Position. [ . . . . ]

7.a. Abstract connexion: Touching, concerning; in the matter of, in reference or regard to. The regular preposition employed to define the subject-matter of verbal activity, as in to speak, think, ask, dream, hear, know about; to be sorry, pleased, perplexed about; to give orders, instructions, information about; to form plans, have doubts, feel sure about.

So “in reference or regard to . . . the [relevant] subject-matter”—i.e., this webpage, the one you’re currently reading (assuming anyone is still reading)—requires turning once again to the trusty OED: 

blog, n. Computing. Brit. /blɒg/, U.S. /blɑg/ Forms: 19– blog, 19– ‘blog

Shortened ‹ weblog > n.2

. . . . . . .

weblog, n. Computing. Brit. /ˈwɛblɒg/, U.S. /ˈwɛbˌlɔg/, /ˈwɛbˌlɑg/ [‹ web n. + log n.1 Compare later blog n.] [ . . . . ]

2. A frequently updated web site consisting of personal observations, excerpts from other sources, etc., typically run by a single person, and usually with hyperlinks to other sites; an online journal or diary.

So—that’s what this website is “About.”