Explanation:
Box 1: Table extension
Isolate all new vendor exclusion codes as a new assembly by creating a table named VendExclusions.
Implement the Excel integration for the Vendor Exclusion List form.
The table extension object allows you to add additional fields or to change some properties on a table provided by the Dynamics 365 Business Central service. In this way, you can add data to the same table and treat it as a single table.
Box 2: Unique key
Create an index for the table named PrimaryIdx that uses the following fields: CustAccount, ItemId, VendAccount.
Box 3: Build and synchronize the database.
A project property lets you specify that the synchronize operation for the database should be performed every time that you build the project. This can be useful when you're making changes to the table structure for an application. Each time that you build, you will know that the database is synchronized with the tables as they are defined in the project.
Reference:
https://docs.microsoft.com/en-us/dynamics365/business-central/dev-itpro/developer/devenv-table-ext-object
https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/dev-tools/build-operations#synchronizing-the-database-at-each-build

Reference:
https://community.dynamics.com/365/financeandoperations/b/howtodynamics365/posts/how-to-import-and-export-project-in-dynamics-365

Explanation:
Box 1: Computed
Computed field: Value is generated by an SQL view computed column.
During read, data is computed by SQL and is fetched directly from the view.
Box 2: Computed
Box 3: Virtual
Virtual field:
Is a non-persisted field.
Is controlled by custom X++ code.
Read and write happens through custom X++ code.
Virtual fields are typically used for intake values that are calculated by using X++ code and can't be replaced by computed columns.
Box 4: Virtual
Virtual field is a non-persisted field.
Reference:
https://docs.microsoft.com/en-us/dynamics365/fin-ops-core/dev-itpro/data-entities/data-entity-computed-columns-virtual-fields