It looks like there is no room on the server.

Check with the websiteprovider and see how much space you have, and what you have used.

You should find it in the portal of your website provider. Else ask your provider by mail.

Do you have a lot of big pictures? Check also the size of your project in step5 analyse website.

If it is very big you could use the free optimizer of x5 to make the project smaller.

If this is the case then delete the project on your server (select all and use red cross in top of x5 after you connected to server (like in your prtscrn)

Then do a full upload.

https://www.websitex5.com/en/utility.html

Or try again later maybe there is a mailfunction at your providers server.

Hope this helps

PS see also:

https://x10hosting.com/community/threads/ftp-filezilla-upload-error-552-disk-full-please-upload-later.180380/

https://www.inmotionhosting.com/support/community-support/file-management/552-disk-full-please-upload-later-via-ftp

So this is not an x5 issue but more an hosting issue.