Help! Repo not letting me push to Github.

I have committed this document many times and all of the sudden R is throwing the following error. How can I fix this?

git push origin refs/heads/master
To GitHub - jessica-scazzero/who_uses_cash: Explores micro US survey data to analyze what factors drive cash usage on an individual level
! [rejected] master -> master (fetch first)
error: failed to push some refs to 'GitHub - jessica-scazzero/who_uses_cash: Explores micro US survey data to analyze what factors drive cash usage on an individual level'
hint: Updates were rejected because the remote contains work that you do
hint: not have locally. This is usually caused by another repository pushing
hint: to the same ref. You may want to first integrate the remote changes
hint: (e.g., 'git pull ...') before pushing again.
hint: See the 'Note about fast-forwards' in 'git push --help' for details.