Questions about example sentences with, and the definition and usage of "Harp"

A: All she did was harp on about Taylor Swift's new album
All he did was harp on about cars
All I did was harp on about cats

'Harp on about' means to keep talking about or to never shut up about something/someone.

A: 'He plays the harp so beautifully'.
'I need to get new strings for my harp'.
Also,
'Don't harp on about it'. In this case 'harp' means to keep on talking/complaining about something.
e.g.
'I know I forgot your birthday but don't keep on harping about it'.
'He just harps on all the time'.