This group of settings is for items that you likely will not need to access regularly; these are typically set-it-and forget-it settings that you may review upon initial set-up.
The Alignment option within the Grow settings allow you to choose which side the widget displays on the screen: Bottom Right or Bottom Left.
The Horizontal Offset setting is the amount of pixels the widget appears from the left or right side of the screen.
The Vertical Offset setting is the amount of pixels the widget appears from the bottom of the screen.
You can experiment with these settings if you want to adjust the widget position slightly.
Avoid Selectors help move the Grow widget above elements that may also be positioned in the same place on your screen.
Learn more about Avoid Selectors.
At the bottom of the Advanced tab section, you'll see a Disable Grow code, which you'll want to use if you wish to disable all of Grow from displaying on a particular page/post.
Learn more about Disabling Grow on a Post.