Battlefield 5 is not on the Steam platform, so searching for it will yield no results.
The Battlefield series is a first-person shooting game produced and published by EA. If you want to play Battlefield 5, you need to purchase and experience it on EA's own game platform Origin.
Extended content
The Steam platform is a game platform that Valve hired Bram Cohen, the inventor of BitTorrent (BT download), to personally develop and design. The Steam platform is currently one of the largest comprehensive digital distribution platforms in the world. Players can purchase, download, discuss, upload and share games and software on this platform.