altar
Brazen altar, type of the Cross upon which Christ, our whole burnt-offering offered Himself without spot to God (Hebrews 9:14).
height
(Cf) (Exodus 25:10). The altar of burnt offering is double the height of the mercy-seat. The atonement more than saves us -- it glorifies God (John 17:14).
shittim
That is, acacia.
wood
The wood (Christ's humanity), completely inclosed in brass, must have become completely charred by sacrificial fires.
Compare (Hebrews 10:5-7).