알았어(aratsseo) : I got it enough 알아서(araseo) : by one's own ex) 그런 쉬운 일은 네가 알아서 해! (Do such easy things by your own!)

The above comments are correct but you also really have to be careful with whom you say it to and how you say it. You would really only say this to a close friend or a person who is much younger than you. It can come off as rude depending on the situation. 알겠어 sounds a bit softer but it's still only used for people you are very close with!

Simply it means I got it:)

I am assuming that you mean 알았어 and that means “I knew”, “I know”, “I understand”, etc. It is the past tense of 알아. When you use it in a sentence it is best translated as “knew”. An example would be “나는 날씨에대 해 알았어 (I knew about the weather)”. However, it is also used alone to express that you have understood what was just said to you. Like if your friend was giving you directions, your mom was reminding of something, or a person was giving you a task to do your response could be 알았어. In this scenario the better translations would be along the lines of “I know”, “I understand”, “understood”, or “got it”. In English we can flip the verb tense between past and present but in Korean it is always past because you had to understand what was being said in the past, even if the past was five seconds ago. I hope this helps:)