When you download theCronTab module,  the following files get copied to the CronTab folder from the URL mentioned in the recipe, and these files contain the module data.

1. CronTab.ps1xml
2. CronTab.psd1
3. CronTab.psm1

The Import-Module cmdlet registers the cmdlets available in the module into the PowerShell session and makes the module ready for use. The Import-Module cmdlet is run against the module manifest, which is the psd1 file. 

When you run the Get-Command cmdlet, you get a list of all the cmdlets available in the module.