EVerything you host on internet consume some space whether it is image, video or an email. So your Google accounts also come with some storage space. Each Google service offers some storage space limit to its users. If you run out of this limit, you wouldn’t be able to store extra in your accounts.
The simple solution for this is to check your Google accounts storage space at regular intervals. You can check how much space is left in your accounts by visiting Google Basic Storage usage page.
If your usage is high and you need more extra storage, you can also buy more space from the page.
Link: Check your storage limit
I hope this post will help you manage your Google storage space.