Note also the meaning and usage of "figure something out": figure something out INFORMAL Solve or discover the cause of a problem: He was trying to figure out why the camera wasn’t working. Sometimes, people just mix up "figure" and "figure out" and the sentence you quoted might mean more to you if you thought of it as "I can't figure out where I am. The best I can figure (out) is that I am ..."

See this fuller definition/explanation from the Oxford Dictionary: "[WITH CLAUSE] INFORMAL , chiefly North American Think, consider, or expect to be the case: I figured that I didn’t have much of a chance [WITH OBJECT]: for years, teachers had figured him for a dullard" Note that the usage is "informal" and mainly used in North America.

It means something like "my best guess". My best guess is that I'm somewhere around...