Other than just "playing", two super important things to practice are ear training and transcribing. They both reinforce each other and improve every aspect of your musical abilities, including understanding of theory.

For ear training (eg intervals), I use the Perfect Ear app. [1]

For transcribing, I use software called "Transcribe!" [2]. You can repeat specific parts of a song, and also slow it down without altering the pitch (known as "time stretching").

You can also use Audacity for transcription but Transcribe! does tend to be a bit easier to use.

  - [1] https://www.perfectear.app/
  - [2] https://www.seventhstring.com/xscribe/overview.html