This is God's preamble to His instructions for all the feasts in this chapter. This is the foundation upon which the rest of the instructions are built. Notice that God both claims all the feasts - He says these are My feasts - and He also tells us, in general, what their focus should be. They are feasts of the LORD, meaning each one of them must be observed in reference to Him. God declares at the outset that the feasts are for Him and about Him. If that focus is lost, then the feasts become our days rather than God's.
Richard has been going through each of the feasts and showing how they point to Christ. That's one comparison for us - that's what all the feasts have in common. For decades, the focus of the church has been on how the feasts fit into a prophetic sequence, yet we are learning that they are about so much more. They teach us about God Himself. They are feasts of the LORD, and each one points to the Messiah.