15 And one shall take from it a handful of the fine flour of the grain offering and its oil and all the frankincense that is on the grain offering and burn this as its memorial portion on the altar, a pleasing aroma to the LORD.
16 And the rest of it Aaron and his sons shall eat. It shall be eaten unleavened in a holy place. In the court of the tent of meeting they shall eat it.
An offering with a pleasing aroma to God is not necessarily something which literally smells nice, though with the oil and frankincense there was sure to be a literal nice smell in this case. It is the attitude of the giver and the joy and gratitude towards God which ultimately makes the offering pleasing to God. Metaphorically, a pleasing aroma is a God-honouring attitude in giving.
Notice that Aaron and sons, the priests of Israel, were to eat the cooked offering. The priests were busy serving God and his people and did not have time to work for a living. Their livelihood came from their work, as commanded by God. This was one way that God provided for them. Another was via tithes which were monetary offerings of a sort.
The final thing to note is that the bread was unleavened. That is, it was made without yeast to make it rise. This would make the bread very dense, longer lasting (for a reminder of God's deliverance of Israel and their travel during the exodus of Egypt), and pure. Yeast is often used as imagery to represent sin or evil.