The NIV has several other possible translations for this verse (as does some other Bibles). These are the various translations: "The LORD our God, the LORD is one"; "The LORD our God is one LORD"; "The LORD is our God, the LORD is one"; "The LORD is our God, the LORD alone." Each translation is similar but slightly different.
The first commandment, "Thou shall have no other god's before me," could be interpreted to mean other gods are okay, just don't place them before me. The fifty cent word for worshiping several gods is syncretism.
God is telling the Israelites that He alone is God. There is no other. This is not God discussing the Trinity. He was reminding them of this fact as they prepared to enter a land where the people worshiped many gods. The LORD proved none of the gods in Egypt could withstand Him. The same would be true in the Promised Land. Moses' warning was prescient because the Israelites worshiped not only the LORD but a slew of other gods before their Babylonian captivity.
Notice how this chapter ties love, obedience and righteousness together. The chapter begins with the command to keep God's statutes and rules in verses 1-3, with the first specific instruction given in verse 5, "You shall love the LORD your God with all your heart and with all your soul and with all your might." The rest of the chapter primarily discusses why the Israelites would love and obey the LORD. Their desire to live obediently would be reflected in the way they were always teaching their children who God is, and all He did and is doing for them. It is only by following God's direction that life will go well for the nation. Verse 25 links righteousness with obedience, "And it will be righteousness for us, if we are careful to do all this commandment before the LORD our God, as he has commanded us."
Jesus explicitly says in John 14:15, "If you love me, you will keep my commands." 1 John 3:9 says whoever practices righteousness is of God. 1 John 5:3 says the way to show your love of God is to keep his commandments. It seems obvious, doesn't it? If I love someone, I want to please them. And that response is for someone who is imperfect. How much greater should my love and obedience be for my perfect Lord and Savior?
LORD our God, You alone are God; there is no other. We confess to worshiping other gods before You. But our desire is to love You with all our heart, soul and might. We know the only proper response to You is love. Righteous lives flow out of love for You evidenced by obedience. May love, obedience, and righteousness be obvious in us.