Warm welcome to p-f. I think the guys above covered "Luger" ammunition, but this link might also help to explain the term:
https://en.wikipedia.org/wiki/9%C3%9719mm_Parabellum
It is a bit of a coincidence the historic pistol and ammunition share the same name.
I am very far from an expert, but have found good online sources of practice ammunition, bought in larger quantities (multiples of 1,000) to be near the lowest prices. You may know this, but there three common "types" (weights actually) of the bullets in 9mm - 115 grain, 124 grain, and 147 grain. Depending on powder load, and weight, they will definitely feel different in your Glock 19.
I've settled on a couple providers lately:
www.sgammo.com
and
www.targetsportsusa.com
There are certainly others. FM is one of them; and I've happily shot many thousands of rounds of Freedom over the years. I also have had an occasional, and noticeable malfunction attributed to using FM. So I've opted not to order. But many use them without issue.
For me, I tend to order anything from Federal or Speer; usually Federal American Eagle or Speer Lawman, typically in 124 grain. This gives me good performance which matches point of impact / point of aim for my chosen carry load, Federal HST 147, in my gun(s) (Glock 19, Glock 43X), for how I shoot (lefty). YMMV.
Good luck!
This is a great place to ask questions. A lot of folks here have forgotten more about Pistols than I will ever know. Ask away.
Rich