The phrase "new enemies" refers to people or groups that were not considered as threats before, but are now seen as opposition or adversaries. Full definition
That kind of stuff does change up the flow a bit, as do a handful of new enemy types. (giantbomb.com)
There's a bunch of new enemy types and bosses to try out all your moves on too. (thatvideogameblog.com)
The game becomes more challenging and fast paced as you progress through with new enemies appearing with different weapons / abilities. (xboxgamerreviews.com)