Question: I was looking for a easy way to delete hundreds of test site in a modern SharePoint online env. MS flow didn't to the trick, so I was looking into PowerShell.

```
Set-Location -Path C:\scripts

#Connect to SPO
$tenantName= "companyName"
$username = "emiel@companyName.be"
$password = "SuperSavePassword" | ConvertTo-SecureString -AsPlainText -Force
$cred = New-Object System.Management.Automation.PSCredential -ArgumentList $Username,$Password

Connect-SPOService -Url https://$tenantName-admin.sharepoint.com/ -Credential $cred
Connect-MsolService -Credential $cred
Connect-AzureAD -Credential $cred
Connect-PnPOnline -Url https://$tenantName-admin.sharepoint.com/ -Credentials $cred 

```

Anytime I'm trying to `Get-PnPUnifiedGroup` I get an error saying s'thing like:

> 
> Get-PnPUnifiedGroup : Exception while invoking endpoint
>  <https://login.microsoftonline.com/2092f441-2e68-4313-9252-4794a2e05343/oauth2/token>
> 
> 
> 

Yet, my account is a global admin on the tenant.

EDIT:

I found another way, in which I don't have to use 'PNPunifiedGroup'

```
$sites= Import-Csv C:\Users\xxx\Downloads\DemoToDelete.csv
ForEach ($s in $sites)
{
$group = Get-MSolGroup -SearchString $s.Title
Remove-MsolGroup -ObjectId $group.ObjectId
Remove-SPOSite -Identity $s.SiteUrl -Confirm:$False
}

```

This deleted like 50% of the sites provided in .csv

Answer: 
Totally depends on what functionality you need, every feature has its own importance and set of functionality. If you don't require it for your site collection no need to activate it. By default all the importance once which are required are activated based on site template. There is description about every feature and what it does, check the description and see if you feel any feature is important for your purpose, you can activate it. please remember we should not bog down site with features components available eventually which are not going to use.
Just as Siddharth said, the features needed depends on your plan for the SharePoint Site. And available features vary with different site templates. 

<https://docs.microsoft.com/en-us/sharepoint/sites/sites-and-site-collections-overview>

You can have a check on this doc and get a feeling about site templates. Practice with the templates seem to fit your requirements and check the features available with their descriptions below.

If that does not help, just search with the confusing feature, there are many introductions. The very first thing is to get a clear idea of your final goal or requirements.