The first short paragraph outlines and reiterates the sanctity of the Sabbath. It is declares the Sabbath to be a day of solemn rest (which we have sadly forgotten) and holy convocation. The regulations concerning the Passover are reiterated, as well, specifically concerning the identification of it as a feast in the Jewish calendar, and the dietary instructions to eat only unleavened bread. And on the first day they were to have a holy convocation. And on the seventh day, there would also be a holy convocation (Sabbath).
What is the significance of the Sabbath? God created us. He knew our limitations. He knew our need for rest, and he knew our need for fellowship with God. Therefore, He called for His people to take a day to rest and connect with God. Societies often program day after day full of activity, work, and play. Be sure to give God and yourself a day to recharge and reconnect. You need it!
Devoted To You 