Hrvatski means Croatian in Croatian.
It also has a property of an adjective, as in something that has to do with Croatia. This makes sense, since Croatia is Hrvatska in Croatian.

When you go on some website or somewhere else where there is a description of a language that the document is spoken in, it would never say Croatian. Instead, almost every document (including all the non-English ones) would rather say Hrvatski.
This node is here to dissolve your confusion as to what Hrvatski really means, in case you ever cared.