What is the Biblical Hebrew for El Nahsah-God who forgives?

Answer 1

El Nahsah does not mean God who forgives.

I don't know whether you want the English for "El NASA", or the Hebrew for "God who forgives", so I'll translate everything. FYI, all of these translations are the same in Classical Hebrew as they are in Modern Hebrew.

1. El nasa depends on how you spell nasa in Hebrew:

el nasa (קל נשא) = God carried
el nasa (קל נסע) = God traveled

2. God who forgives = el shĕsōlĕ'akh (קל שסולח)

Answer 2

Perhaps you're talking about Psalm 99:8

יהוה אֱלֹהֵינוּ אַתָּה עֲנִיתָם: אֵל נֹשֵׂא הָיִיתָ לָהֶם וְנֹקֵם, עַל-עֲלִילוֹתָם

ADONAI Eloheinu, atah anitam: El Noseh hayita lahem venokem al-alilotam

"ADONAI our God, you answered them, you were a forgiving God to them, though you took vengeance of their misdeeds."

It doesn't say El Nahsah. It says El Noséh (literally "God who carries"). This is a very flowery way to say God who forgives. In other words, God "carries" the thing needing forgiving.

Otherwise:

El Nahsah does not mean God who forgives. I'll translate everything. FYI, all of these translations are the same in Classical Hebrew as they are in Modern Hebrew:

1. El nasa depends on how you spell nasa in Hebrew:

• El nasa (אל נשא) = God carried
  
• El nasa (אל נסע) = God traveled
  
• El na'aseh (אל נעשה) = God became

2. God who forgives = El sōleach (אל סולח)