SharePoint has the ability to crawl and index network file share content, including Office files, PDFs and other content. Searching a network share from Windows Explorer is usually very slow, but once SharePoint indexes the content, search results are returned nearly instantly. SharePoint also recognizes the security on the file shares it crawls, meaning SharePoint will only return content to people who have rights to those items in the file share.
If you are the owner of a network file share, or you use a file share you'd like to be able to search from SharePoint, please let your SharePoint farm administrators know so they can add the crawl source to the SharePoint Search Service Application. They will need the file share owner or the file server administrator to give the SharePoint crawler service account read rights to the file share, then your SharePoint farm admin can add the file share UNC path (\\servername\share) to the SharePoint search content sources and schedule a crawl of the content. Once the crawl completes, people will be able to search the file share content from SharePoint. The content should be incrementally crawled at least nightly so people will be able to find new content soon after it is added. SharePoint 2013 also has a continuous crawl feature, which means crawls are running all the time rather than scheduled. This feature can have impacts and drawbacks, so it should be tested and evaluated in your organization to ensure that it doesn't negatively impact the SharePoint farm, file servers or the network during business hours. You may need to scale your search servers in order to successfully use this feature. You can read about the difference between incremental and continuous crawls here: