That just means that you can't realize infinite precision, infinite length, or infinite time. That's fine, and is probably correct. Good and Real by Gary L. Drescher (2006) talks about it, but large parts of the book are "wrong" (in the same way Occam's razor is wrong, not the same way the flat Earth is wrong). I'd say almost all of it is fixable though, so it's useful. I'd look out for the parts on the multiple worlds hypothesis of quantum mechanics (no better than modern version of the Copenhagen interpretation, unless you think wave function collapse is a physical event that has a cause), gives more respect to Wolfram's cellular automata ideas than it should (it should give almost no respect at all), and accepts evidential decision theory more than it should. Sabine Hossenfelder and modern causal decision theorists would have problems with it, but it's a good introduction for people who think human brains are magical and/or better than computers.