need understanding of what ppm means in the hydroponic world

I need some help understanding the termonology in what is meant of chk'n ppm, I understand the term of ph & EC

ppm =

Parts
Per
Millon


what it means is how many units of ferts to a millon parts of water

1300ppm= 1300 parts of fert within a millon parts of water.

Thanxs 4 the n4 I had looked it up on google