Can View Only: Members with this permission can access all the content on your Board and its future updates, but they cannot modify the content. They can also send content using the keyboard or Chrome Extension. Additionally, they can re-send the invite link to other members. This is the default setting when adding members via the invite link.
Can View and Share: Members with this permission can access all the content on your Board and its future updates, but they cannot modify the content. Additionally, they can add other members to the Board via email. They can also send content using the keyboard or Chrome Extension.
This is the default setting when adding members via email.
Check out this article (iOS/Android) to learn about access rights and Boards ownership.