I can see the confusion. The official Adobe definition of a Visit is "A sequence of page views in a sitting" - Visit. However, this includes single-page visits.
Think of it this way: generally one Unique Visitor will have one or more Visits. Each Visit will have one or more Page Views. There are exceptions where a visit may not contain any page views but only events.
Yes, it does. A visit is also or more commonly known as a session which usually last for about 30 minutes by default. A visitor can have a visit with one or more page views and a single page visits is a sub-portion of all visits, simply put, all visits with a single page view count as "Single Page Visits".
NOTE that the single page visits metric will be high for single page applications if the necessary measures aren't put into place to send in virtual page views.