Go to your KDP Dashboard and login.
When you login you can see your sales today and other information.
Click on "Orders" on the left side. This will show by default, the current month sales.
You can use the filters under date to pick various time periods.
To see prior month royalties:
Click reports after logged into your KDP dashboard
Then on the left menu, click "Prior Month Royalties"
Click the choose a month choice to see what your royalties will be.
Keep in mind Amazon pays at the end of the month, 2 months after the sales were made. So if it the end of June, you are getting paid for April sales you made.