The Welcome package provides a simple startup screen for the Flow framework and is part of the default distribution. If you develop your own application, you don't need it at all.
If you want to use the Flow framework, please have a look at the Flow documentation
This package uses the "Work Sans" typeface, released under the SIL Open Font License v1.1 by Wei Huang, see https://github.com/weiweihuanghuang/Work-Sans.