There are two separate "Find New Connections" pages, using different logic.
1) The Collaborate > "Find New Connections #1" page lists out all people from your branches who could potentially be related to other people online from other researchers.
Ancestors: When searching for ancestors of your people, it lists those who do not have parents identified, do have a birth date and place, and where other researchers do have this same surname in the same location as yours, and up to 110 years before yours. For these it would be possible that the parents or earlier ancestors of yours are already online in another researcher's branch, or perhaps are in the same family if not ancestors.
An example:Descendants: When searching for descendants of your people, it lists those who have a birth date and place, and where other researchers have this same surname in the same location as yours, no parents identified, and up to 110 years after yours.
Clicking the name from your data opens up the page for your person. Clicking the name of the researcher opens a list of their people with this name, in this timeframe. Also shown is the most recently updated date from the other researcher's data, and in yellow if within the past month -- so that you can focus on recent updates, vs. older ones you may have already looked at.
Also helping you to focus on recent updates, putting a date in the date field at the top fill filter the list to show only those matches with updates since this date.
Note: This is limited to only those who have at least an approximate birth date, a birth state / country, and a birth county / province. So be thorough where possible!
2) "Find New Connections #2" uses broader logic to connect people, where the above page is a little more narrow. #2 lists anyone in your branch where you have 2 or more people with the same surname, in the same county, and no parents. Maybe they are siblings or cousins, and could use more research. For each in the list, it shows the count from your branch, the count from all branches with the same name in the same county, and the most recent date these were updated.