nodemon.ps1 cannot be loaded because running scripts is disabled on this system.

PowerShell execution policy doesn’t allow to run scripts. It  is a safety feature that controls the conditions under which PowerShell loads configuration files and runs scripts to prevent the execution of malicious scripts. On a Windows computer you can set an execution policy for the current user, or for a particular session. or use a Group Policy setting to set execution policies for computers and users. To enable the options this are the steps you can follow:

1. Open a PowerShell as an administrator
2. Command for checking the current execution policy. If you dont set any policy before you will get ‘Restricted’.

Get-ExecutionPolicy

3. Run below command to remove restriction for current user

Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

Resource

https://docs.microsoft.com/en-us/powershell/module/microsoft.powershell.core/about/about_execution_policies?view=powershell-