A spoke is a scoped application that contains flow actions that can be used in Flow Designer. Spokes allow developers to create reusable actions that can be shared across applications and instances.
Spokes - Product Documentation: San Diego - ServiceNow
Create a spoke - Product Documentation: San Diego - ServiceNow
Flow Designer Spokes - ServiceNow Developers

The ServiceNow platform is designed to create applications that use forms, workflow, and reporting to solve business problems. Forms are used to interact with data stored in tables, workflow is used to automate and orchestrate processes, and reporting is used to visualize and analyze dat a. The platform does not require low-level programming libraries or multimedia features, as it provides standard tools and technologies for application development.
Reference = ServiceNow Certified Application Developer Exam Specification, Application Development Platform - ServiceNow

https://docs.servicenow.com/bundle/paris-servicenow-platform/page/administer/flow-designer/concept/spokes.
html
A spoke is a scoped application containing Flow Designer content dedicated to a particular application or record type. Flow Designer provides a set of core actions to automate Now Platform processes. You can add application-specific core actions by activating the associated spoke.
Reference: https://community.servicenow.com/community?
id=community_blog&sys_id=7b3af354db93ab80afc902d5ca9619bc

Application Access settings on a table control which operations external applications (in other scopes) can perform. The main controllable operations are:
* Can create
* Can read (query)
* Can update
* Can delete
From Development Handbook 4.0.4, p. 192:
"Application access settings determine whether another scope can read, write, create, or delete records from this table... Execute is not a valid database operation - it pertains to script includes or other executable logic."

Explanation/Reference:
Reference https://docs.servicenow.com/bundle/orlando-application-development/page/build/applications/ concept/c_ApplicationScope.html#r_ExampleNamespaceIdentifiers