# who had a reputation as pillars

Pillars are posts that support a building. Here it refers to important leaders. Alternate translation: "who were known to be important leaders" or "who were known to be important leaders of the church"

# recognized the grace that had been given to me

"recognized the grace that God had given to me" or "recognized that God had been kind to me"

# gave the right hand of fellowship to Barnabas and me

Grasping and shaking the right hand was a symbol of fellowship. Alternate translation: "welcomed Barnabas and me as fellow workers" or "welcomed Barnabas and me with honor"