I'm still in my learning phase and I make many small projects as I learn. Is putting all of them on Github a good idea, if I want to put it on my resume in the future, or would having too many repositories on Github a bad thing?
Repeating what others have said, and adding a bit:
it's fine to have a bunch of repositories.
"pin" the ones you would most like to talk about in a job interview
"archive" projects that you're completely done with
be aware that pinned repositories and whichever repository has the most recent activity is probably the ones that I - an interviewer - will pick to ask questions about.
Just archive projects that you don't want to talk about. That's pretty much all "archive" is for. It's a message to the world "I don't use this anymore. Don't ask me about it."