Exodus 16:36, "Now an omer is one tenth of an ephah," is a statement about the volume or quantity of the omer in relation to the ephah. It's essentially defining the omer using a standard unit of measure already familiar to the Israelites (the ephah).

Here's a breakdown:

Omer: This was a dry measure used by the Israelites to measure grain, particularly the manna they collected in the wilderness.

Ephah: This was a larger dry measure, also used for grain and other dry goods.

"One tenth of an ephah": This explicitly states that the volume contained in one omer is equivalent to one-tenth of the volume contained in an ephah. This provides a quantitative relationship.

Purpose and Significance:

Standardization: This verse helps standardize the omer as a unit of measure. People might have been unsure exactly how much manna to collect. Referencing it to the known ephah provided clarity.

Practical Application: The Israelites needed to know how much manna to gather daily (Exodus 16:16). This verse clarifies exactly how much an "omer" (per person) actually was, relative to a larger standard measure. It served as a reliable guideline for the daily manna collection.

Foundation for Later Laws: Understanding the omer's volume is crucial for understanding other commandments involving offerings, first fruits, and tithes, which often used the omer or its related units.

In simple terms, it's like saying, "A liter is one-tenth of a decaliter."