Here is the video version, if you prefer it:
Brace expansion is used to pass multiple arguments to a command. (Barrett, 2016) An example:
mislav@mislavovo-racunalo:~/Linux_folder$ echo my{File1,File2,File3}
myFile1 myFile2 myFile3
So the shell performed its expansion and I have 3 filenames because of that. Note that there are no spaces between the commas and the next letter. If I put a space, I would get:
mislav@mislavovo-racunalo:~/Linux_folder$ echo my{File1, File2, File3}
my{File1, File2, File3}
Useful to know.
Hope you learned something new!
References
Barrett, D. J. (2016). Linux pocket guide (3rd ed.). O’Reilly Media. Page 30