The masons is a fraternity.
It originated with stone layers (operative masons), but has been expanded to include non-stone workers (speculative masons). The speculative masons make use of the same tools – the square, compass, plumb, and level, each having a different meaning.

The main point of masonry is to make a good man better.
The only real “secrets” are the modes of recognition. This goes back to the days when a mason was offered work and paid based on the ability to give the word, and sign of a master mason – thousands of years back when a person would travel and work as a mason. The ancient guilds would have a secret work/sign – that would keep out un-skilled impostors.