I am using macOS Sierra(unfortunately), and for example when I typed man curl to see what the -LSso flag does, it opens the man page in a editor which resembles vim slightly. I know its not Vim since it doesn't have :syntax on and you can't use :wq and so on.
The heading of the page says man(less).
I can't find what editor this might be and I'm learning vim and emacs configurations. Or maybe it's just a man page and no editor is used?
Less is a program similar to more (1), but which allows backward movement in the file as well as forward movement. Also, less does not have to read the entire input file before starting, so with large input files it starts up faster than text editors like vi (1). Less uses termcap (or terminfo on some systems), so it can run on a variety of terminals. There is even limited support for hardcopy terminals. (On a hardcopy terminal, lines which should be printed at the top of the screen are prefixed with a caret.)
Commands are based on both more and vi. Commands may be preceded by a decimal number, called N in the descriptions below. The number is used by some commands, as indicated.
-- Copied from less man page