Looking into this, if you have a hold on the Shopify Payments gateway - you may notice a message displayed on your Shopify admin homepage. I would suggest checking your spam/junk folder to see if the email may have landed there. With that being said, the hold on the gateway will not prevent your customers from completing the checkout on your online store - it is a hold on the payouts.
In this case, it would be best to reach out to our live support by logging into your online store using the Contact Us page. This will allow us to securely verify you as the store owner.
Once you successfully login - you will be directed to the Help Center. Select the topic that you would like assistance with to locate the options to Get Support and speak directly with a Support Advisor about the hold.