Literally "앞뒤 안보고 한거예요" could be translated into "i did it without looking back and forth" But implied meaning is that I put into an action except considering about what will happen after the action.

I might be still missing something but I'd like to give it a try =) in Korean, there are following grammar patterns with 것 (or its shortened form - 거) - verb stem+(으)ㄴ 것 (or 거)+이다 for the past verb stem+는 것 (or 거)+이다 for the present verb stem+(으)ㄹ 것 (or 거)+이다 for the future thus, basically you can say almost the same using two different approaches - a verb itself or one of the mentioned grammar patterns - 했어요 or 한 것이에요 or 한 거예요 = done, have done 해요 or 하는 것이에요 or 하는 거예요 = do 하겠어요 or 할 것이에요 or 할 거예요 = will be doing in addition, consider that 것 litelally means 'thing' which gives you an effect like this: 뭐 해요? What do you do? 뭐 하고 있어요? What are you doing? 뭐 하는 거예요? What is the thing that you do? summing up, 한 것이에요 means something like - It is (for the 이에요) the-thing-that-was-done (for the 한 것)