Exodus 28:37 is part of the detailed instructions for making the High Priest's attire, specifically the golden plate or medallion for his turban or mitre. Here's a breakdown of the meaning:

"You shall put it on a lace of blue...": The "it" refers to the golden plate (mentioned in the previous verse, Exodus 28:36) that was inscribed with the words "Holy to the Lord." This golden plate was to be attached to the High Priest's turban or mitre (head covering) using a cord or lace made of blue thread.

"...and it shall be on the sash...": The sash here is referring to the High Priest's turban or mitre, not the garment worn around the waist. The golden plate, attached by the blue lace, was to be placed on the front of the mitre.

"...on the front of the sash it shall be.": This reiterates that the golden plate, with the blue lace, should be prominently displayed on the front of the High Priest's mitre. This placement would ensure that the inscription "Holy to the Lord" was visible for all to see.

In essence, the verse describes how the golden plate, a symbol of the High Priest's consecration and dedication to the Lord, was to be securely and visibly attached to the front of his head covering using a blue cord.

Significance:

Holiness: The placement of the "Holy to the Lord" inscription on the High Priest's forehead was a constant reminder of his sacred role and responsibility to represent the people before God. It also symbolized that his thoughts and actions should be dedicated to God.
Visibility: The prominent placement ensured that everyone could see the High Priest's sacred calling.
Blue: The color blue is often associated with the heavens and divinity in the Bible, further emphasizing the sacred nature of the golden plate and its purpose.

In short, the verse is a specific instruction about the proper and symbolic placement of a key element of the High Priest's garments.