Tax Implications withdrawing from acorns invest account

Hello, I am hoping for some guidance. About 2.5 years ago I start using Acorns, and made an Acorns invest account where I was investing my “spare change” and depositing $6 into the account every week. I have now reached about $1,000 and would like to withdraw this money. It says possible tax implications and id like to know if that is true and what that means. 

Thank you