See the minimums above, surpassing the recommended system requirements will allow you to turn the graphics up the more your system outranks them.
Hit Start > Run, type dxdiag and press enter.
If you're on Windows XP, make sure your version supports it. 99% will not have a problem with these unless using a very old version of windows.
See notes on shader model 3.0 to find out how to see your processor model).
You can play offline afterward, but will have to be connected in order to start the game for the first time. Please Note that The Sims 4 requires an internet connection for initial activation. Here are the minimum and recommended requirements for running The Sims 4. The Sims 4 does not require a particularly powerful machine, but some of the requirements may be beyond a budget PC or laptop's abilities. The Sims 4 Requirements Can My PC Play it? & Shader Model 3.0 Help