Reddit glossary
What is Spam (on Reddit) on Reddit?
On Reddit, spam is posting the same links or promotion again and again, or posting mostly to promote yourself.
Reddit has sitewide rules against it, and each community has its own too. Spam filters can hide your posts without telling you.
It is not only about volume. One post that has no other purpose than pushing your link can count as spam.
If you are promoting something
The safest test is to ask whether the comment would still be useful if your link was removed. If not, rewrite it.