From now on; hereafter — referring to the period following the present (used as noun/adverb).
今後はもっと注意します。
I will be more careful from now on.
会社は今後の方針を発表した。
The company announced its policy going forward.
今後ともよろしくお願いします。
I look forward to your continued support (or: I hope we can continue to work well together).