Those numbers indicate how people in each family branch between you and the person you are connected to.
Families are indicated by the green and yellow groups.
These numbers match the numbers of people in each green and yellow family group between the first name and the last name.
Family groups are all one colour until a marriage happens, and then the colour changes for the next family group until the next marriage, and so on.
If you have 3 numbers at the top then there are 3 family groups between you and the person you are connected to.
If you get numbers like this 1 - XX - 1 - then you are connected to the person via your spouse and their spouse. That also means that your spouse is biologically related to the spouse of the person being connected to.
So you get one colour for yourself, a whole block of colour for the next family and then one last colour change for the last spouse which should be the person being connected to.
I had one of those for Cary Grant this week. I discovered that my spouse is an 8th cousin to Virginia Cherrill Martini who was married to Cary Grant.
Basically the FEWER numbers you have up there, the more closely related you (or your spouse) may be.
HTH