anyone know the translation to this kata name?my sensei told me but it slipped my mind.

How about,

peaceful and confident.


oldman

Number four of the peacful mind set, or of the children's set (Pinan).

My Korean instructor told me that it was peaceful like the still water/peaceful but also holding the power of the ocean.

check this link out for the meaning
http://www.reikijutsukai.org.uk/kata/reikikata_013.htm

Heian means peaceful, as in a peaceful mind.

The idea is if you iknow the applications, you have a peaceful mind as to the understanding of basic but robust self defense - armbars, throws, escapes, takedowns are all the Heians. Fits in with the idea of having a basic martial competency before reaching Ydansha.

The original name was Pinan. This simply meant belonging to a child/children. They were, children's kata, with some applications specifically for smaller people, or the Kanku/Channan kata split up, (as they are long and difficult).

Yondan simply means fourth, as you can guess.