When you make a sale and the customer pays via PayPal, you'll receive an email from PayPal letting you know about the transaction.
Stripe does the same, however you may need to check a box to ensure this email is getting sent to you.
Here's how to do that:
Click your profile picture in the top right hand corner and select Profile
Scroll down to the Notifications section and check the box of any emails that you'd like to receive. We'd recommend selecting them all. It'll look something like this: