Harley Quinn show on HBO Max

Hiii, I wanted to ask y'all a question related to that show. I started watching it mainly bcs I heard that Harley and Poison Ivy are gfs in the show and I'm trying to watch more shows with some wlw representation. However, I'm still kinda new to the whole Batman and DC universe in general, even though I've watched some Batman films and know the whole dynamic beetween Batman and the Joker in general, I'd like to know if there are any shows or movies I should probably watch to get more of an idea of the context in which the Harley Quinn show is happening. Could you guys help me, please? I'd really appreciate it :)