Why not use Bootstrap from the official website, when working with Vue? Well, we definitely could do that, but Bootstrap relies on jQuery, and since we want to keep everything JavaScript-related running through Vue, we'll have to use a project that's built for this purpose exactly: BootstrapVue.
Let's begin by visiting the project website at https://bootstrap-vue.js.org/. Here, we can get acquainted with the project in general. Specifically, it would be useful to read the documentation at https://bootstrap-vue.js.org/docs#vue-cli-3 , which discusses the use of BootstrapVue inside a Vue CLI 3 project.