What does it mean that Israel will belong to the Jewish people when the Messiah will come? When will this happen and how?
The Land of Israel belongs to the nation of Israel even today. The Land Covenant that was made with Abraham is eternal, and is true of today no less than the Messianic Era, as the verse states: “I will establish My covenant between Me and you and between your offspring after you, throughout their generations, as an everlasting covenant, to be a God to you and to your offspring after you; and I will give you and your descendants after you the land of your sojourns—the whole land of Canaan—as an everlasting possession; and I shall be a God unto them” (Genesis 17:7-8).
The great significance of the Land Covenant is underscored by Tehillin (105:8-10): “He remembered His covenant forever—the Word He commanded for a thousand generations—that He made with Abraham, and His vow to Isaac, and He established it with Jacob as a statute, for Israel as an everlasting covenant, saying: ‘To you I shall give the land of Canaan, the lot of your inheritance.'”
Indeed, there is a unique relationship between Israel and the Land, as the Vilna Gaon writes:
“Who is like Your nation Israel, one nation upon the earth.” For both of them are singular: Israel and the Land of Israel—Israel among the seventy nations, and the Land of Israel among all the lands. Just as [God] is called the “God of Israel,” so He is called “God of the Land” … therefore even the revelation of Torah is in the Land of Israel, as the Sages have said, “The air of the Land of Israel imbues wisdom;” and even prophecy is confined to the Land of Israel . . .
Yet, the possession of Israel over the Land will only become actual, in the fullest sense of the word, when the Messiah will come. Although even today, most of the Land of Israel is under the political autonomy of Jews — a remarkable achievement after two millenia of exile — our possession continues to be disputed, and continues to be partial. In the Messianic Era, this will no longer be the case.
When this will come? We cannot know. But we know (and sense) that the time is nearing, and we hope and pray that we shall see the coming of the Messiah, and the final gathering of Jews to their homeland, speedily.