You'll have to enter "Yes" or "No" in the Taxable column to indicate the taxability of your products and services. This way, you can import them in QuickBooks successfully.
Here's how to import your products and services:
In your QuickBooks Online, click the Gear icon, then select Import Data.
Click Products and Services from the list.
Select the Browse button, then find the Excel file where you save it and click Open.
Hit Next, then map your fields to QuickBooks fields.