You can add as many Fields as you want for every Type. Here are Field categories:
Text — a single line of text.
Email — an email address.
Number — a number with formatting options (can be formatted as Integer or Decimal number, or Money with selected currency).
Single Select — select from a list of options.
Multi Select — select several options from a list of options.
Date — a date or date range with an option to include time.
Checkbox — a single checkbox.
URL — a link to some resource.
More complex fields
Relation. Connect Types together. For example, Feature may have many Tasks, or many Teams can be assigned to a Feature.
Formula. Calculate things. For example, total effort of all Tasks related to Feature.
Rich Text. Collaborate on a document. Great for a Feature description or an Article content.
Lookup. Show a field from a related Type.
Files: upload and attach files to Entity — PDFs, slides and videos.
Assignments: assign people to Entity.
Avatar: custom avatar for every Entity — useful for Teams, Departments and Customers.
Comments: discuss Entity in a comments thread.
Workflow: visualize Entity’s state (Open, In Progress, Done — by default)
Type is useful when it has Fields. One way to add Fields is from any Entity of the Type. For example, open any Post and add a new Field:
The other option is to open Type from Customize Apps screen and add new Fields there:
Delete & Rename Field
To Delete or Rename a Field, navigate to Customize Apps, select Type and click … near required Field: