I would recommend BirdNET which is "a joint project of the K. Lisa Yang Center for Conservation Bioacoustics at the Cornell Lab of Ornithology, and Chemnitz University of Technology". It's using neural networks and can identify over 3000 species.
Birding
Post Photographs of Birds, share your Gear, get Tips for better shots or help others with their Birding
BirdNET is very good. it starts recording on booting the app and suggests with probability. You can save soundfiles, get direkt links to wikipedia and can share files with inaturalist or other third party apps. I use it everytime I need to know which bird is singing
BirdNET is great. I was also just recommended Merlin, which does photo ID too. I haven't had an opportunity to test the sound feature, though.
I've had a lot of success using Merlin Bird ID (by the Cornell Lab of Ornithology) to figure out what birds I'm hearing around my house. It listens and detects likely birds based on the songs, and then provides a lot of additional information about the bird and sample songs. It also has other features for helping identify birds visually.
It's been very informative for understanding that many of the distinct sounds I'm hearing regularly actually come from the same bird. I didn't realize how much variation a single bird could have until I started using this app.
As for learning the calls, that's going to come down to standard learning techniques. Merlin Bird ID doesn't have any flashcard style learning built in.