I'm not sure what your guitar came with, but the 18:1 means that for every 18 revolutions of the tuning peg,
the string post turns one revolution. A very fine ratio.
Most Fender guitars come with a 12:1, or maybe a 14:1.
My Epi Les Paul, made in Korea in 2008, came with 18:1 Grover tuners.
To check your tuners turn the peg, counting how many complete turns it take to turn
the post one complete revolution.