Hi @Boneckrh19,
The Publish button is part of the CDS add in for Excel, get it installed to your Excel from Insert > My Addins > Store > Search for "PowerApps"
Then when you Open in Excel an Entity the right hand pane that pops up in that excel workbook is the CDS add in, in which you wil lsee the data from your Entity. at first, you need to refresh, then changes you makein excel when Published are sent to CDS instantly.
Note you can add more entities to your workbook from the gear button in the addin, select the design mode, then youcan add more entities.
See attached.
Note handling data via this add in isnt so much straight forward, so i suggest you play with it before you consider real data. I dont mean to terrify you but there are things like you cant publish until you clear all filters, also the look up field is 2 columns not 1, and the copy means copying 2 fields not 1. etc
Finally, you will fall in love with CDS i promise! Welcome onboard..