how do i know if i have the latest version on my MacBook pro

If you are running Mojave, because menu : About This Mac panel tells you that you have macOS 10.14._ , visit System Preferences : Software Update and see if it tells you that you are up to date, or if a pending update appears there.

Prior to Mojave, check the Mac App Store's Update panel for pending operating system updates.

Latest version of what? If you mean macOS, go to Apple menu > About This Mac. The last version released was macOS Mojave 10.14.6.

Note that older Macs will not run the current version.