<#
	.SYNOPSIS
		Set item attribute to 'Hidden'
#>

# For a single file, you can change the attributes property, like this:
$file = Get-Item .\your_folder -Force
$file.attributes = "Hidden"

# To hide everything within a folder, you can use Get-ChildItem, like this:
Get-ChildItem -Path "your_path_here" -Recurse -Force | ForEach-Object { $_.attributes = "Hidden" }