It's a standard for android apps to use a nsec manager like nostr:nprofile1qqs827g8dkd07zjvlhh60csytujgd3l9mz7x807xk3fewge7rwlukxgpzpmhxue69uhkummnw3ezumt0d5hsz9thwden5te0wfjkccte9ejxzmt4wvhxjme0qy88wumn8ghj7mn0wvhxcmmv9uzk8xwq|s #Amber app to store your nsec locally on your device without giving every nostr client or website access to it.

(At least, that's how a pleb would describe it. If you understand more about programming etc. this might be very simplistic or technically wrong...)