He said to them, “It is not for you to know times or seasons which the Father has fixed by His own authority; but you shall receive power when the Holy Spirit has come upon you.” (v.7-8a)
Here we have Jesus answering His disciples question concerning when He would restore the kingdom of Israel which was currently under Roman control. He does not give them a specific answer - no day or time, but stretches them to see that all events are under the loving control of God the Father. Meaning, there are some things we just will not know in this life. Therefore, we are to look to Him Who made all things and trust in His authority.
In the second part of our text, Jesus responds to their concerns (their prayer, actually), by promising them the power of the Holy Spirit. Having this inward comforter, they could “rest” in not needing to know everything and “know” that the power of His Spirit would be with them always.
The same is true for us. To know the future is not precisely what we need. We need peace, rest, and the assurance that God is always with us. We can only find it in Him who holds the future in His hands. While answers to concerns are valuable and He often gives us such answers down the road, simply trusting in God and the comfort of His Spirit is infinitely better.
The Truth: “The Lord is my strength and my shield; My heart trusted in Him, and I am helped; Therefore my heart greatly rejoices, And with my song I will praise Him.” (Psalm 28:7)