make heads or tails of

make heads or tails (out) of (someone or something)

To understand someone or something. This phrase is usually used in the negative to convey the opposite. After spending hours working with the new piece of software, I still could not make heads or tails out of it. I can't make heads or tails of that new guy in accounting. Sometimes, he's really friendly, and then other times he acts like he's never met me before.
See also: head, make, of, tail
Farlex Dictionary of Idioms.

make heads or tails of someone or something

Fig. to understand someone or something that someone has said. (Usually with the negative.) I can't make heads or tails of Fred. No one can make heads or tails of this problem.
See also: head, make, of, tail
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

make heads or tails of

To understand: I couldn't make heads or tails of the report.
See also: head, make, of, tail
American Heritage® Dictionary of the English Language, Fifth Edition.
See also:
  • be (not) as black as (someone or something) is painted
  • (not) give a toss
  • (not) give a fig
  • (not) care a fig
  • fig
  • (not) care a toss
  • (not) care a hoot
  • caring
  • count for
  • count for (something)