Artie is right, of course, but here's a shortcut to opening System Profiler:
1. Click the Apple menu (upper left of the screen).
2. From the drop-down menu, click About This Mac.
3. In the About This Mac window, click More Info. That opens System Profiler. SP will give you every bit of information that you ever (or never) wanted to know about your Mac.
OS 10.14.4, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365