Toggle Multiple Google Accounts

If you need to use multiple Google accounts on the same browser at the same time then you will need to switch between the different account.  Doing so is as easy as clicking the user icon at the top right of the screen and then going to "Add account" once you sign-in with the second account then you can go back and forth between the two accounts by clicking the profile picture.

An alternative method to using two accounts at once is using a separate browser to sign into the other account.  For example, you can sign into your main account in the Google Chrome browser while you sign into a secondary account using the Firefox browser.