According to: http://confluence.atlassian.com/display/CONF35/Blog+Posts+Macro

When you set the parameter content=excerpts it should display short excerpts from each blog posts. After each excerpt, the words 'Read more...' will offer a link allowing the user to click through to the full blog post, if the content is over 500 characters long.

However if you install the US English language pack (in Confluence Admin > Plugins) and set UserName > Settings > Language to English (United States) you will see that the "Read more..." link will change to Read more & help;. If you change the language back to Automatically detect browser setting it works normally.