I like this as a name element in Gülizar, Gülistan, Gülnaz and Gülbahar. The meaning-rose-is pretty, but this name is a bit plain on a girl. It works better as a standalone on a boy.
Gül is also an Azerbaijani name. And, Gül is also used as a masculine name in Turkish and Azerbaijani. Some evidence for this is that Gül is also used as a name element in unisex and masculine Turkish and Azerbaijani names, such as Gülbahar, Gülnar, Gülnaz, Gülşen, etc. However, Gül is more common for females. So, I think that the "Usage" of this name should be changed to read, "Turkish, Azerbaijani", and that the "Gender" of this name should be changed from "Feminine" to "Feminine & Masculine".Sources: https://www.names.org/n/gul/about https://forebears.io/x/forenames/gül
The name means "rose" in Turkish, this Turkish word had once come into use in Bulgaria, besides the word "roza", which is the Bulgarian word for "rose".