Hi @Kinozoom, 

Thanks for being a part of Community! Without a source, most likely they have been added due to general engagement, rather than subscribing to a newsletter, etc.
It is possible for profiles to populate as active profiles from within your account, without having subscribed to a List/placed an order/manual upload etc. Klaviyo creates a profile for any visitor that is cookied on your connected website. Klaviyo cookies visitors who have:

• Been identified via a Javascript Identify API request (through Klaviyo's Identify API)
• Submitted to a Klaviyo Signup Form (or an integrated Signup Form depending on the integration)
• Clicked into your site from a Klaviyo email
• Added  ?utm_email=myemail@example.com to the URL

This thread also sheds some more light on the source for profiles:

 I hope this helps. Let me know if there are any followup questions. 

~Chloe