Signer flow is an advanced setting on your PDF xEdit page and part of the Signer Experience settings. You can use it to control how signers move through their documents. For simple forms, the most common setting is to have auto-forwarding ON.
This means the signer will be guided by the system on the following field automatically. If you combine it with field ordering, you can achieve the maximum level of control on how your recipient(s) progress through a document and little place for error.
Please note signer flow is ON by default and a per-document setting. If you want a different signer flow for another template, you will have to access its respective editing page to amend it.
Check this video guide on how to locate it and enable/disable it: