A set of modules, templates, style settings, and global content that can be mixed and matched to create websites are HubSpot Themes and the idea behind them is to make better websites with perfection.
A theme contains different type of files for your website, including
Coded Templates: A set of templates for your website, including a homepage, about page, landing page, and blog templates falls under the category of coded template.
Modules: With a set of unique theme modules you can add to content using the theme.
Global Content: Content repeated on multiple pages, such as a website header or footer. You can edit global content directly from the drag and drop page editor.
Theme Settings: Style settings for templates using a theme, including fonts, spacing, and colors.
Themes being a package cascades throughout the HubSpot app in various places to enable an efficient content creation experience. Developers can use themes to build a design system for content creators to work within. Whatever amount of flexibility, or guardrails can be built into a theme to meet the needs of your business.