.gitignore exclude folder but include specific subfolder

Question

I have the folder application/ which I add to the .gitignore. Inside the application/ folder is the folder application/language

Answer 1

gitignore - Specifies intentionally untracked files to ignore.

Example to exclude everything except a specific directory foo/bar (note the /* - without the slash, the wildcard would also exclude everything within foo/bar):

$ cat .gitignore
# exclude everything except directory foo/bar
/*
!/foo
/foo/*
!/foo/bar

Another example for WordPress:

!/wp-content
wp-content/*
!/wp-content/plugins
wp-content/plugins/*
!wp-content/plugins/my-awesome-plugin

More informations in here: https://git-scm.com/docs/gitignore