I'm excited to hear that you're considering QuickBooks Online for your business's bookkeeping. I hear what you're saying about wanting to be able to use the program in your preferred language as I'm sure this will help with ensuring the accuracy of what you're entering and easy of use overall. I'm happy to say that French is absolutely an option for QuickBooks Online.
As Fiat Lux has pointed out, it's as simple as signing up for an account from our French sign up page. Doing this will automatically display the program and its features in French. If you've already signed up for a QuickBooks Online account, however, don't worry. You can still change it to French. Here's how.
Once this is done, the program will appear in French. Certain things to keep in mind with doing things this way is that some items that were already set up, such as the chart of accounts and sales tax codes, will still display in the originally configured language of the program. Therefore, if you want a fully French account, you may want to consider starting a new one.
I'll be here should you have more questions. Don't be afraid to reach out.