From Why can people edit my posts? How does editing work? in the help:
If a user without edit privileges proposes an edit that does not comply with the guidelines above, it is ordinarily rejected in the review process. Even if a bad edit is applied to a post, other users will generally fix it. Users with sufficient reputation may elect to roll back the post to a previous version (by viewing the revision history of the post and selecting the version they would like to display).
Additionally, any user who submits many rejected edits will be banned from suggesting further edits for 7 days.
There is additional information in the SE FAQ How do suggested edits work?
The ban is automatically applied by the system when a large number of suggested edits by you were rejected in the past week (at least 5 more than one-third of your accepted edits). From that link:
(rejects - (approvals / 3)) >= 5, you will be auto-banned.
Note that "rejects" is the count of rejections made by human users/moderators only, rejections made by the Community bot as a result of a conflict are ignored.
You can review each of your suggested edits and their outcomes via your Activity page. Clicking on the "rejected edit" links will take you to details of the reviews. For example, on your most recent rejected edit:
Review the information in the links above before making your next suggested edit (the ban clears automatically). In particular (again from the help centre):
Edits are expected to be substantial and to leave the post better than you found it. Common reasons for edits include:
- To fix grammar and spelling mistakes
- To clarify the meaning of the post (without changing that meaning)
- To include additional information only found in comments, so all of the information relevant to the post is contained in one place
- To correct minor mistakes or add updates as the post ages
- To add related resources or hyperlinks
I would particularly stress that editing code to fit your own personal layout preferences is not welcomed here. It is acceptable to edit code so that it displays without scroll bars, or to fix egregiously unreadable originals, but that is about it.