Automates a few of the pesky challenges when getting data from Sheets up to BigQuery:

1) Creating tables: the Connector automatically reads your tab's data columns + types, and creates tables in BigQuery that will play nicely with them.

2) Scheduling upload jobs: the Connector creates timed triggers on your behalf to schedule upload jobs.  

3) Error reporting: the Connector checks with BigQuery on the status of your upload jobs, so you're never in the dark.

The Connector also allows you to pull down data from BigQuery into Sheets - useful when building spreadsheet templates (like forecasts) that depend on the data you have living in BigQuery.