דַּבֵּר אֲלֵהֶם כֹּה אָמַר אֲדֹ-נָי ה' הִנֵּה אֲנִי לֹקֵחַ אֶת עֵץ יוֹסֵף אֲשֶׁר בְּיַד אֶפְרַיִם וְשִׁבְטֵי יִשְׂרָאֵל חֲבֵרָו וְנָתַתִּי אוֹתָם עָלָיו אֶת עֵץ יְהוּדָה וַעֲשִׂיתִם לְעֵץ אֶחָד וְהָיוּ אֶחָד בְּיָדִי
Say to them, “Thus says Hashem, G-d: Behold, I take the stick of Joseph, in the hand of Ephraim, and the Tribes of Israel his companions, and I place them together with the stick of Judah and make them one stick, and they will be one in My hand."
In this prophecy, G-d discusses how he will reunite the two kingdoms – the kingdom of Judah, comprising Judah and Benjamin, and the kingdom of Israel, made up of Ephraim and the rest of the Tribes. He symbolizes this by having Ezekiel join two sticks together, making them one. The Metzudas David explains that the one large stick, formed by joining the two smaller sticks, is a royal scepter, which G-d will hold in His metaphorical hand. (The Metzudas David doesn’t say as much but perhaps the scepter symbolizes the nations’ reunification under the Davidic dynasty.)