I'll oversimplify a bit, but here you go. In economic terms, liberalism is a market oriented economy, and the current iteration of neoliberalism is marked by social welfare cuts and tax cuts for the rich with "trickle down" effect in mind (allegedly). That ideology is shared by both the democratic and republican parties. The difference between communists and liberals in the sense the word is most often used, is that economic approach, and from that perspective both liberals and conservatives are "liberal".

Now the common use of the word is a bit different, but that's almost exclusively US from what I can tell. Hexbear is also international though, and liberal is a common term for right wingers where I'm from for example.

Hope I could help.