When any user try to share any file from external sources like image or video etc. Then your app will be shown in ‘share with’ list, when you allow receive shared.
In simple words, you can get the shared file in your app.
Just like when we try to share any image then WhatsApp is shown in share with list, your app will also be shown there.
You can trigger any action by using Got received shared block.
Know more about it here
https://docs.kodular.io/components/screen/#got-received-shared