Numbers 7:89 meaning

The tabernacle had been set up and consecrated. The LORD had begun to dwell in the tabernacle (Exodus 40:34 - 35). So, Moses went into the tent of meeting to speak with Him (v. 89). During his time in the "tent of meeting," he heard the voice speaking to him from above the mercy seat that was on the ark of the testimony, from between the two cherubim (v. 89), as was described in Exodus 25:17 - 22. The LORD spoke to him from the holiest place in the tabernacle, and it represented His dwelling place amongst His people.

Verse 89 touches on two other verses concerning where Moses was when hearing the voice of God. From Leviticus:

"Then the Lord called to Moses and spoke to him from the tent of meeting."
(Leviticus 1:1)

From Exodus:

"There I will meet with you; and from above the mercy seat."
(Exodus 25:22)

Verse 89 clarifies that Moses went into the tent of meeting to speak with Him, he heard the voice speaking to him from above the mercy seat that was on the ark.

The voice came from above the mercy seat, the place where the grace and mercy of God could be found. This "mercy seat" was located on the lid of the "ark of the testimony." And it was in this way that He spoke to him. This was another indication that Moses was the LORD's spokesman to the people. God spoke to the Israelites through Moses, and Moses could go before the mercy seat to speak to God on behalf of His people.

The mercy seat was so-called because the sins of the people were atoned by blood sprinkled on the mercy seat each year, on the Day of Atonement (Leviticus 16). This likely represents the throne of God, as the tabernacle represents the true tabernacle of God in heaven (Hebrews 9:24). It is interesting to note that at the throne of God there is both mercy as well as judgement (2 Corinthians 5:10).

For the LORD to speak to Moses after the 12-day dedication of the tabernacle was an indication that He approved of and accepted the offerings of the 12 tribes.