Investors & landlords

I can not understand the tern Safe harbor.    processing my 2018 (late) I encounter this safe harbor telling me I was okay to take it.  and by error I said okay, or whatever was theway to accept.  I don’t want this safe harbor.   I rent 2 units and live in one.  I am the manager and owner and do a lot of the work when people move out and I have to paint… that part completely, Is on me.  so how is that safe harbor apply to me?  How can I see th reply to his reply/comment?