What do you mean by Bootstrap well?
Bootstrap well is nothing but a container that makes the content appear sunken. Sometimes it may also give an inset effect on the webpage. Thus, a developer can create a well and also wrap the content in the well with the help of <div> and class .well. The content would appear as per your wish.
🔗Reference : stackoverflow.com
🔗Source: Bootstrap Interview Questions and Answers for Freshers and Experience