altar:

a platform on which priests presented offerings in worship to God.

The altar of burnt offerings (also called the altar of sacrifices) was in the Court of the Priests in front of the Temple. Every morning and afternoon, people would gather in the Temple to worship God. Some would bring animals to be sacrificed. Priests would slaughter the animals by the posts near the altar, then burn them on the altar. Then while the people in the Temple courts were praying, a priest would take coals from this altar into the Temple interior and place them on the altar of incense. He would then burn incense on these coals to symbolize the many prayers rising to God.