Salesforce (formally Salesforce1) is Salesforce’s smartphone app.  The look and feel very much resembles the new Lightning Experience interface.  Nearly all of your data is viewable and editable from the mobile app, but setup and configuration is best left to the desktop interface.  Quick actions are a popular tool for automating several updates with simple click. 

Here’s a quick video demonstration: https://youtu.be/ARHl2apZ3q0

Here’s more information:  https://trailhead.salesforce.com/en/salesforce1_mobile_app/salesforce1_mobile_app_intro

Here’s links to install the two mobile apps:

Android: https://play.google.com/store/apps/details?id=com.salesforce.chatter&hl=en

iOS: https://itunes.apple.com/en/app/salesforce1/id404249815?mt=8