Here are some possibilities:
* I understand: This is the most common translation and works in most situations.
* I comprehend: This is a more formal word that emphasizes the act of fully grasping something.
* I get it: This is a more informal and colloquial way of saying you understand.
* I see: This is a shorter and more casual way of saying you understand.
* I follow: This implies you are following a line of reasoning or argument.
The best translation will depend on the specific situation and what you want to convey.