The Hugo codeblock highlight plugin allows users to highlight specific lines within code blocks in Obsidian using the Hugo syntax. By adding the `hl_lines` option to code blocks, users can highlight single lines or ranges of lines. Additionally, users can select lines directly within the code block and highlight them using a right-click menu. This functionality enhances the readability and visual appeal of code snippets, making it easier to focus on specific parts of the code. The plugin is optimized for Obsidian's Live Preview and Source modes.