When a site more frequently updates its content it tells Google to come visit more often, giving it a chance to be reviewed for new things and potentially rank higher. If you have a blog that can be updated once or twice a week and occasionally update the main website with new content, that should be helpful.
Freshness of the content is part of the Google ranking factor. “Query Deserves Freshness”, in short QDF, is a ranking algorithm by Google. It essentially means: “Search requests that deserve up-to-date search results”. By using QDF Google is trying to identify the topics and search requests where the user has a desire for new and current content, to position up-to-date information on these search results.