A git ignore file is just a text file that follows traditional bash file structure.
So if you wanted to ignore the entire current folder you'd type:./
./ means current directory
Also if you type *.jpeg
you would ignore any file with the extension .jpeg at the end of it
So if you want to exclude a folder name you'd type a like that looks like this ./<folder name>/
a common folder that is excluded is node_modules, because it stores local packages that clutter your workspace, so you'd type ./node_modules/
in your gitignore file.